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SALT DYNAMICS AND PRODUCTIVITY ENHANCEMENT
UNDER ALLEY CROPPING SYSTEMS
By
Abdul Rasul Awan
89-ag-1028
M. Sc. (Hons.) Agri. Forestry
A thesis submitted in partial fulfillment of requirements for the degree of
Doctor of Philosophy
in
FORESTRY
DEPARTMENT OF FORESTRY AND RANGE MANAGEMENT
FACULTY OF AGRICULTURE
UNIVERSITY OF AGRICULTURE, FAISALABAD
PAKISTAN
2015
i
The Controller of Examinations,
University of Agriculture,
Faisalabad.
We, the supervisory committee, certify that the contents and form of the thesis
submitted by Mr. Abdul Rasul Awan, Reg. No. 89-ag-1028 have been found satisfactory and
recommend that it be processed for evaluation by the External Examiner(s) for the award of
degree.
Supervisory Committee
Chairman _______________________________
Dr. Muhammad Tahir Siddiqui
Co-Supervisor _______________________________
Dr. Khalid Mahmood
Member _______________________________
Dr. Rashid Ahmed Khan
Member _______________________________
Dr. Muhammad Maqsood
ii
DEDICATED
TO
MY DEAR FAMILY
WITH
DEEP GRATITUDE
FOR THEIR SUPPORT
iii
ACKNOWLEDGEMENTS
I am extremely grateful to the glory of ALLAH, the compassionate and the merciful,
whose divine power enabled me to complete this thesis. The Holy Prophet, Muhammad
(PBUH), the torch owner to this world and his praise has helped me a lot during the
completion of present project. My sincerest thanks and grateful appreciations are also due to
my praise worthy supervisor, Dr. Muhammad Tahir Siddiqui, Professor, Department of
Forestry and Range Management, whose affectionate supervision and keen guidance had
fetched fruits in the form of this dissertation.
I have no words to express my profound gratitude to Dr. Khalid Mahmood, Deputy
Chief Scientist and Head, Soil Science Division, Nuclear Institute for Agriculture and
Biology (NIAB), Faisalabad whose admirable help guided me to execute this project
successfully. My gratitude to Dr. Rashid Ahmed Khan, Professor, Department of Forestry,
for his dedicated concentration and decisive opinions during my research period.
Appreciation to Dr. Muhammad Maqsood, Professor, Department of Agronomy, for his
suggestions during these studies are highly acknowledged. Thanks are also due to successive
Directors of NIAB (Dr. Javed Akhter and Dr. Muhammad Hamed) for their courtesy for
allowing me to conduct research work at NIAB.
Appreciations for commendable help of all friends, colleagues and well wishers at
NIAB, Faisalabad namely; Dr. Sajid Nadeem, Dr. Zafar-ul-Haq Hashmi, Dr. Muhammad
Akhtar, Dr. Babar Manzoor Atta, Mr. Muhammad Rizwan, Mr. Muhammad Younis, Mr.
Munawar Hussain and Mr. Nasrullah Khan along with all team members working at BSRS,
Pakka Anna towards the completion of this dissertation would always be remembered.
At the end, sincere thanks to all of my family members who supported me morally for
accomplishment of the present thesis work.
(Abdul Rasul Awan)
iv
DECLARATION
I hereby affirm that the contents of this thesis titled "Salt dynamics and productivity
enhancement under alley cropping systems" are the product of my own research and no part
has been copied from any published source (except the references, standard mathematical or
genetic models/equations/protocols, etc.). I further declare that this work has not been
submitted for award of any other diploma/degree. The University may take action if the
information provided is found inaccurate at any stage.
(Abdul Rasul Awan)
89-ag-1028
v
Table of Contents
Chapter Description Page
1 INTRODUCTION 1
1.1 Environmental degradation and food security 1
1.2 Soil salinity: a menace to agricultural productivity 2
1.3 Approaches to overcome the menace of salinity and sodicity 3
1.4 Agroforestry: a boom for enhanced biomass production 4
1.5 Interactions in agroforestry systems 5
1.6 Global forest resources 6
1.7 Forest sector situation in Pakistan 7
1.8 Justification for the present project 8
2 REVIEW OF LITERATURE 10
2.1 Intercropping as a customary farming practice and present scenario 10
2.2 Biomass productivity status in different cropping systems 10
2.3 Two-facet effect of intercropping systems on biomass production 11
2.3.1 Enhanced biomass production in intercropping systems 11
2.3.2 Reduced biomass production in intercropping systems 12
2.4 Biomass productivity in agroforestry systems 13
2.4.1 Enhanced biomass productivity in agroforestry systems 13
2.4.1.1 Enhanced biomass productivity in agrisilviculture systems 13
2.4.1.2 Enhanced biomass productivity in silvipastoral systems 16
2.4.2 Reduced biomass productivity in agroforestry systems 18
2.4.2.1 Reduced biomass productivity in agrisilviculture systems 18
2.4.2.2 Reduced biomass productivity in silvipastoral systems 20
2.5 Light factor in agroforestry systems 21
2.6 Effect of saline water on soil properties 23
2.7 Effect of farm yard manure under saline conditions 25
2.8 Effect of salinity on nutrient elements 26
vi
2.9 Integrated nutrient management in agroforestry systems 27
2.9.1 Application of inorganic fertilizers in alley cropping systems 27
2.9.2 Application of organic fertilizers in alley cropping systems 29
2.10 Alley cropping systems for salt-affected soils 31
2.11 Agroforestry systems for reclamation of problem soils 34
2.12 Economic assessment in agroforestry systems 35
3 MATERIALS AND METHODS 37
3.1 Study area, site and climate 37
3.2 Soil and irrigation water characteristics 37
3.3 Components of agroforestry systems 40
3.4 Treatments, experimental design and field layout 40
3.5 Tree and crop management 43
3.6 Light intensity 44
3.7 Biomass estimation of understorey components 44
3.8 Tree growth estimation 44
3.9 Soil characteristics monitoring 45
3.9.1 Analytical procedures 45
3.10 Statistical analysis 49
4 RESULTS AND DISCUSSION 50
4.1 Study 1: Interactive effect of varying levels of nitrogen and farm
manure on biomass production of wheat in open field, Acacia and
Eucalyptus based alley cropping systems with different light
intensity regimes.
50
4.1.1 Wheat growth and production 50
4.1.1.1 Plant density 50
4.1.1.2 Plant height 53
4.1.1.3 Leaf area 56
4.1.1.4 Number of tillers m-2 59
4.1.1.5 Number of grains spike-1 62
4.1.1.6 1000-grains weight 65
vii
4.1.1.7 Grain yield 68
4.1.1.8 Straw yield 71
4.1.1.9 Aggregate biomass (Biological yield) 74
4.1.1.10 Harvest index 77
4.1.2 Tree growth and wood production 80
4.1.2.1 Tree bole volume 80
4.1.2.2 Mean Annual Increment in wood production 82
4.1.3 Annual biomass productivity of different systems 85
4.1.4 Variation in soil chemical properties under sole and alley cropping
systems
88
4.1.4.1 Soil pH 88
4.1.4.2 Soil electrical conductivity 94
4.1.4.3 Sodium adsorption ratio (SAR) 100
4.1.5 Discussion 106
4.1.5.1 Wheat growth and production under sole and alley cropping
systems
106
4.1.5.2 Tree growth and wood production under sole plantation and tree
based systems
109
4.1.5.3 Biomass productivity under different systems 110
4.1.5.4 Soil properties variation in different cropping systems with
application of amendments
111
4.1.5.4.1 Soil pH 111
4.1.5.4.2 Soil electrical conductivity 112
4.1.5.4.3 Soil sodium adsorption ratio 113
4.2 Study 2: Interactive effect of varying levels of gypsum and farm manure
on biomass production of para grass in open field, Acacia and Eucalyptus
based alley cropping systems with different light intensity regimes
114
4.2.1 Grass growth and production 114
4.2.1.1 Stolon height 114
4.2.1.2 Culm length 117
viii
4.2.1.3 Number of tillers per plant 120
4.2.1.4 Fresh biomass 123
4.2.1.5 Dry biomass 126
4.2.2 Tree growth and wood production 129
4.2.2.1 Tree bole volume 129
4.2.2.2 Mean Annual Increment in wood production 131
4.2.3 Annual biomass productivity of different systems 133
4.2.4 Variation in soil chemical properties under sole and alley cropping
systems
135
4.2.4.1 Soil pH 135
4.2.4.2 Soil electrical conductivity 141
4.2.4.3 Sodium adsorption ratio (SAR) 147
4.2.5 Discussion 153
4.2.5.1 Para grass growth and production under sole and alley cropping
systems
153
4.2.5.2 Tree growth and wood production under sole plantation and tree
based systems
154
4.2.5.3 Biomass productivity under different systems 155
4.2.5.4 Soil properties variation in different cropping systems with
application of amendments
156
4.2.5.4.1 Soil pH 156
4.2.5.4.2 Soil electrical conductivity 157
4.2.5.4.3 Soil sodium adsorption ratio 158
5 SUMMARY 159
LITERATURE CITED 163
ix
LIST OF TABLES
Sr. No. Title Page
3.1 Meteorological data of site during period under study (Apr 2011-Jun 2013) 38
3.2 Analysis of soil at the experimental site 39
3.3 Analysis of irrigation water at the experimental site 39
3.4 Physico-chemical characteristics of farm yard manure used in the
experiments 39
4.1 Effect of fertilizer application on plant density (plants m-2) of wheat grown
in open field, Acacia and Eucalyptus based agroforestry systems
52
4.2 Effect of fertilizer application application on plant height (cm) of wheat
grown in open field, Acacia and Eucalyptus based agroforestry systems
55
4.3 Effect of fertilizer application on plant leaf area (cm2) of wheat grown in
open field, Acacia and Eucalyptus based agroforestry systems
58
4.4 Effect of fertilizer application on number of tillers per plant of wheat
grown in open field, Acacia and Eucalyptus based agroforestry systems
61
4.5 Effect of fertilizer application on number of grains spike-1of wheat grown
in open field, Acacia and Eucalyptus based agroforestry systems
64
4.6 Effect of fertilizer application on 1000-grains weight of wheat grown in
open field, Acacia and Eucalyptus based agroforestry systems
67
4.7 Effect of fertilizer application on wheat grain yield (kg ha-1) grown in open
field, Acacia and Eucalyptus based agroforestry systems
70
4.8 Effect of fertilizer application on wheat straw yield (kg ha-1) grown in open
field, Acacia and Eucalyptus based agroforestry systems
73
4.9 Effect of fertilizer application on biological yield (kg ha-1) grown in open
field, Acacia and Eucalyptus based agroforestry systems
76
4.10 Effect of fertilizer application on harvest index percentage grown in open
field, Acacia and Eucalyptus based agroforestry systems
79
4.11 Effect of amendments on bole volume (m3 ha-1) grown in sole field and
agroforestry systems
81
4.12 Effect of amendments on mean annual increment (m3 ha-1 yr-1) in wood
production of trees grown in sole field and agroforestry systems
84
4.13 Effect of amendments on aggregate biomass productivity (kg ha-1 yr-1) of
different agroforestry systems
87
4.14 Effect of amendments on soil pH in open field (sole cropping) 91
4.15 Effect of amendments on soil pH in Acacia based alley cropping systems 92
4.16 Effect of amendments on soil pH in Eucalyptus-based alley cropping
systems
93
4.17 Effect of amendments on soil electrical conductivity (EC) in open field
(sole cropping)
97
4.18 Effect of amendments on soil electrical conductivity (EC) in Acacia based
alley cropping systems
98
x
Sr. No. Title Page
4.19 Effect of amendments on soil electrical conductivity (EC) in Eucalyptus
based alley cropping systems
99
4.20 Effect of amendments on soil sodium adsorption ratio (SAR) in open field
(sole cropping)
103
4.21 Effect of amendments on soil sodium adsorption ratio (SAR) in Acacia
based alley cropping systems
104
4.22 Effect of amendments on soil sodium adsorption ratio (SAR) in Eucalyptus
based alley cropping systems
105
4.23 Effect of fertilizer application on stolon height (cm) of para grass grown in
open field, Acacia and Eucalyptus-based agroforestry systems
116
4.24 Effect of fertilizer application on culm length (m) of para grass grown in
open field and agroforestry systems
119
4.25 Effect of fertilizer application on number of tillers of para grass per plant
grown in open field and agroforestry designs
122
4.26 Effect of fertilizer application on fresh weight (Mg ha-1) of para grass
grown in open field, Acacia and Eucalyptus-based agroforestry systems
125
4.27 Effect of fertilizer application on dry biomass (Mg ha-1) of para grass
grown in open field, Acacia and Eucalyptus based agroforestry systems
128
4.28 Effect of amendments on bole volume (m3 ha-1) grown in sole field and
agroforestry systems
130
4.29 Effect of amendments on mean annual increment (m3 ha-1 yr-1) in wood
production of trees grown in sole field and agroforestry systems
132
4.30 Effect of amendments on aggregate biomass productivity (kg ha-1 yr-1) of
different agroforestry systems
134
4.31 Effect of amendments on soil pH in open field (sole cropping) 138
4.32 Effect of amendments on soil pH in Acacia based alley cropping systems 139
4.33 Effect of amendments on soil pH in Eucalyptus based alley cropping
systems
140
4.34 Effect of amendments on soil electrical conductivity (EC) in open field
(sole cropping)
144
4.35 Effect of amendments on soil electrical conductivity (EC) in Acacia based
alley cropping systems
145
4.36 Effect of amendments on soil electrical conductivity (EC) in Eucalyptus
based alley cropping systems
146
4.37 Effect of amendments on soil sodium adsorption ratio (SAR) in open field
(sole cropping)
150
4.38 Effect of amendments on soil sodium adsorption ratio (SAR) in Acacia
based alley cropping systems
151
4.39 Effect of amendments on soil sodium adsorption ratio (SAR) in Eucalyptus
based alley cropping systems
152
xi
LIST OF FIGURES
Fig. No. Title Page
1 Agrisilviculture system 41
2 Silvopastoral system 42
3 Effect of different amendments on soil pH under different cropping
systems
90
4 Effect of different amendments on soil EC under different cropping
systems
96
5 Effect of different amendments on soil SAR under different cropping
systems
102
6 Effect of different amendments on soil pH under different cropping
systems
137
7 Effect of different amendments on soil EC under different cropping
systems
143
8 Effect of different amendments on soil SAR under different cropping
systems
149
xii
ABBREVIATIONS AND ACRONYMS
Units and Terms Description
AF Agroforestry
CEC Cation exchange capacity
CP Crude protein
ºC Degree Celsius
dS m-1 Desi simens per meter
Dbh Diameter at breast height
DM Dry Matter
EC Electrical Conductivity
EDTA Ethylene diamine tetra acetate
FAO Food and Agriculture Organization
FYM Farmyard manure
GR Gypsum requirement
Ha Hectare
LSD Least Significant Difference
MAI Mean Annual Increment
Mg ha-1 Mega gram per hectare
M Meter
N Nitrogen
PAR Photosynthetically active radiation
% Percentage
RSC Residual sodium carbonate
SP Saturation percentage
Na+ Sodium
SAR Sodium adsorption ratio
t ha-1 Ton per hectare
xiii
ABSTRACT
Agroforestry has appealed substantial curiosity in recent times because of its radical
potential to preserve and upsurge farm productivity round the globe. Productivity of
agroforestry systems mainly depends upon interaction of growth limiting factors (space,
water, nutrients, shade etc.). Incompatible alley cropping systems (agroforestry systems) may
undesirably upset crop productivity in semi-arid regions on account of intensified
competition. It is, therefore, imperative to develop appropriate alley cropping systems
comprising trees with suitable understorey crop(s) and/or grass(es) with multi-dimensional
complementarity, and application of suitable soil amendments (as nutrient source) to
prevaricate losses in biomass productivity/harvestable product(s)/crop yield(s). Adoption of
agroforestry systems and application of suitable soil amendments simultaneously improve
soil properties and biomass productivity of the ecosystem. The objectives of present research
work were to evaluate effect of application of inorganic and organic amendments in different
types of agroforestry systems in 2-year field experiments on biomass productivity, soil
physiochemical properties and salt dynamics in soil profile. The experiments were carried
out at Biosaline Research Station (BSRS), Pakka Anna, Nuclear Institute for Agriculture and
Biology, Faisalabad, Pakistan. Agroforestry systems included agrisilviculture systems i.e.,
Acacia and Eucalyptus wheat based systems and silvipastoral systems i.e., Acacia and
Eucalyptus para grass based systems established in saline environment. Biomass production
of different components of the systems was recorded with due course of time. In
agrisilviculture systems, more compatibility was perceived in Acacia wheat based alley
cropping systems in contrast to Eucalyptus wheat based systems as the former supported
higher growth of understorey wheat crop. Higher trend in growth and yield parameters of
wheat was observed in open field systems (full sunlight) whereas; it was lower in Acacia-
based systems and lowest in Eucalyptus based system in general (control conditions).
Application of nitrogen fertilizer and farm yard manure in combination further enhanced
biomass production and soil improvement process. Soil properties (pH, electrical
conductivity and sodium adsorption ratio) as affected by different systems showed that these
properties improved much in Acacia-based systems. Application of nitrogen with farm yard
manure further improved the soil properties. In silvipastoral systems, more compatibility was
observed in Acacia-para grass based systems as compared to Eucalyptus based systems
because the former system supported higher growth of understorey para grass component.
Higher trend in growth and production of para grass was observed in open field systems (full
sunlight) whereas; it was lower in Acacia-based systems and lowest in Eucalyptus based
system. Application of amendments (gypsum and farm yard manure) in combination further
enhanced biomass production and soil improvement process. Soil properties (pH, EC and
SAR) as affected by different systems showed that these properties improved much in Acacia
based systems.
1
Chapter 1
INTRODUCTION
1.1 Environmental degradation and food security
Global dynamism of mankind is outcome of his aptitude to utilize natural resources
contained by environment. Certainly, this capability has led to present-day exceptional level
of development of human civilization. However, population influx has forced for imprudent
exploitation of natural resources due to ever increasing societal demands for foodstuff and
firewood production. Thus, exploitation of natural resources has led to ecological distresses
and put serious threats to conservation of environment.
Biomass productivity in ecosystems is follow-on of multifaceted interface between
different land management practices, soil processes and their impact on environmental
features (Doran and Parkin, 1996). Therefore, different forms of land degradation have put
serious threat to “food security” worldwide. Soil degradation originated from salinity and/or
sodicity is a critical ecological restraint which has despondent impact on agricultural
productivity and sustainability, mostly in arid and semiarid regions of the world (Pitman and
Lauchli, 2002; Qadir et al., 2008).
The challenges of providing a growing population with appropriate food, water,
shelter and livelihoods without further degradation of the environment are being taken up
worldwide. The further task is to reverse environmental degradation so as to conserve
precious environmental resources. Unfortunately, environmental degradation is increasing at
a pace that is impairing the productive capacity of our productive lands. The world today is
affected by global challenges such as climate change, food security and environmental
degradation. The recent financial and food crisis have prompted us that the world is changing
quickly and dramatically. Need of the time is to analyze the situation and adopt suitable
measures to conserve resources, optimize biomass production capacity of different agro-
ecosystems.
2
1.2 Soil salinity: a menace to agricultural productivity
i. Nature
Salt-affected soils are categorized by excessive level of soluble salts (salinity) and/or
Na+ in solution phase and cation exchange complex (sodicity). Their genesis may be natural
(primary salinity) or accelerated by human activities (secondary salinity) detailed as:
a. Primary Salinity: The salts (especially Na+ based) activated by weathering of parent
minerals cause primary salinity/sodicity.
b. Secondary Salinity: The salinity developed due to anthropogenic activities like
inappropriate management of natural resources, faulty irrigation practices and higher evapo-
transpiration rate as compared to precipitation (Lambers, 2003; Arzani, 2008).
ii. Extent
The distribution of salt-affected soils is widespread all over the earth planet. Due to
uninterrupted accumulation of salts in soil, millions of hectares of arable land have become
unfit for cultivation round the globe (Flagella, 2002). According to another estimate, 955
million hectare (about 10% of the world’s land surface) is affected by salt-induced soil
degradation i.e., salinity and sodicity (Szabolcs, 1991) and damage to agricultural
productivity is about 25-60% of the world’s irrigated land (Suarez and Rhoades, 1991).
According to FAO (2008), more than 800 million hectare of land over the world is salt-
affected (including both saline and sodic soils) equal to about 6% of the world’s land surface.
In Pakistan, it has been estimated that about 6.8 million hectare land is affected with
varying degree of salinity (Khan, 1998). The crux of the problem is salt-affected and/or
waterlogged farmland resulting from faulty irrigation system/practices.
iii. Effect on land productivity
Salt-affected soils developed either by human induced activities or through natural
phenomenon suffer from diminishing biomass productivity as excessive concentration of
soluble salts in root-zone of soil adversely distress growth and yield of most of the plants. In
short, crop and animal productivity is low in these areas.
3
iv. Mechanism of salinity to affect plant productivity
The damaging effects of salinity on plant growth are associated with low osmotic
potential of soil solution instigating physiological stress, nutritive imbalance, specific ion
toxicity and/or combination of all these factors (Gorham and Wyn Jones, 1993; Marschner,
1995). The shocking effect of salinity on plant growth and yield may be due to suppressed
cell expansion, reduced leaf area and inadequate supply of photosynthates or hormones to
newly developed plant tissues (Munns, 1993). Since carbohydrates are produced through the
process of photosynthesis and photosynthetic rates are generally lower in plants exposed to
salinity (Ashraf and Harris, 2004; Parida and Das, 2005), and this situation leads to limited
water availability and imbalance in nutrient uptake (Pessarakli and Tucker, 1988) resulting in
overall productivity decline of the ecosystem.
v. Economic loss
Economic loss to agricultural production caused due to salinity is expected to be
around $US 12 billion a year in the world which may accelerate in future (Ghassemi et al.,
1995). In addition to this substantial economic loss, there are severe detrimental impacts of
salinity on food security, socio-economic conditions of rural masses and social unrest, etc. In
Pakistan, the economic loss, so occurred, has been estimated around Rs. 20 billion per annum
(Aslam et al., 2009).
1.3 Approaches to overcome the menace of salinity and sodicity
Salinity has disturbed the ecological balance of the ecosystem in arable and forest
areas leading to low productivity against higher demand for food, fuel wood, timber, shelter
etc., thus affecting the livelihood of the farming communities (Abdel-Dayem, 2005). Over
the past 100 years, there had been enormous efforts to improve salt-affected soils in various
parts of the world (Oster et al., 1999). Several approaches such as chemical amendments,
tillage operations (deep ploughing, sub-soiling), water-flooding and introduction of
indigenous and exotic halophytes mitigated the menace to a considerable extent.
In recent times, the vegetation-based management of salt-affected soils has been
publicized as an efficient low-cost amelioration intervention for resource-poor farmers in
many developing countries (Qadir and Oster, 2004). The plants (salt-tolerant grasses, shrubs,
4
trees) grown in this land management option, not only provide plant biomass for using
directly as feed/food, forage, fuel wood, timber, green manure or as raw material for value
added products, but also reclaim the soil, check desertification and enhance the aesthetic
value of salt-affected ecologies at broad-spectrum.
Experts at Nuclear Institute for Agriculture and Biology (NIAB), Faisalabad, Pakistan
have been pursuing research activities to select salt tolerant plants for cultivation to cost-
effectively utilize the otherwise abandoned resources: salt-affected lands and brackish
groundwater. The biomass so produced can be used directly as fuel-wood, timber, forage,
and food/feed or even as raw material for agro-based industrial processing. NIAB has
convincingly demonstrated various options on Biosaline Research Stations near Lahore and
Pakka Anna near Faisalabad, Pakistan. It is an established fact that real benefits of the
technology can be achieved only if it reaches the end-users and is applied on mass scale in
salt-land ecologies. Realizing the need to popularize and benefit the farmers “NIAB-
developed saline agriculture technology” in the field through participatory developmental
activities, a project namely Saline Agriculture Farmer Participatory Development Project
(SAFPDP) in Pakistan has been executed by Pakistan Atomic Energy Commission during
2002-08. SAFPDP has successfully demonstrated that with a right mix of people, adopting
participatory approaches, not only the biomass productivity from such soils can be increased
but also a large scalea adoption of the technology will certainly help improve socio-economic
conditions of the affected rural communities (Aslam et al., 2009).
1.4 Agroforestry: a boom for enhanced biomass production
Agroforestry systems-the systems integrating trees and agriculture have been in
vogue for thousands of years, but the term ‘agroforestry’ was first devised by Bene et al.
(1977). As per definition, “Agroforestry is collective name for land-use systems where
woody perennials (trees, shrubs, etc.) are grown-up in association with herbaceous plants
(crops, pastures) or livestock, in spatial or temporal arrangement, rotation, or both; there are
generally ecological and economic interactions between trees and other components of the
system” (Lundgren 1985). In essence, agroforestry is a practice of land utilization where
trees or shrubs are grown in or around crops or on pasture land, as a means of sustaining
and/or enhancing the productivity of the land.
5
In recent years, agroforestry has gained notable attention of researchers, strategic
experts and policy makers to cope with the drastic demand of food, forage and shelter of
increasing millions of people especially in developing countries, where both forests and
agricultural land are under severe stress owing to population pressure, urbanization and
industrialization. Agroforestry will be supportive to combat soil degradation, improve soil
fertility and increase crop yields. In short, a suitable combination of tree(s) and crop(s)
coupled with appropriate management practices may optimize biomass production by
avoiding competition between woody and herbaceous components in tree based alley
cropping systems (Sileshi et al., 2008).
1.5 Interactions in agroforestry systems
Interactions between different woody and non-woody components of agroforestry
systems can be categorized as positive, negative or neutral, and biomass productivity of the
system as net product of these interactions (Jose et al., 2004). The synergistic
complementarity between the components make it better capture of the limiting resources to
get enhanced biomass production in contrast with monoculture. On the other hand, negative
interaction can lead to antagonism emblazing lower productivity than if trees and crops are
grown individually.
Major limiting factors in agroforestry systems include light, water, nutrients and
space, which result in reduced growth/biomass production (Benavides et al., 2009 and
Reynolds et al., 2007). Competition for water between tree and crop components is likely to
limit productivity in semiarid regions. However, reduced evapotranspiration due to tree shade
effects on understorey plants may increase soil water content as compared to open field
pastures (Joffre and Rambal, 1993).
Basic philosophy regarding higher productivity in agroforestry systems is
complementarity in resource-capture i.e., trees capture the resources which are not available
to the crop due to one or more factors. The theory of niche differentiation- different plant
species obtain resources from different components of the environment, also support the
functioning of agroforestry ecosystems. Tree roots usually extend deeper than crop roots and
are, therefore, capable to attain nutrients and water unavailable to crops as well as utilizing
6
nutrients leached from crop rhizosphere. These nutrients are then recycled via tree leaf fall
onto the soil surface or fine root turnover. Therefore, higher biomass productivity can be
obtained by adopting integrated tree-crop system as compared to monoculture systems
(Sinclair et al., 2000).
Agroforestry has potential for productivity enhancement, soil fertility improvement
and mitigating roles for global environmental degradations (Oyebade et al., 2010).
Agroforestry practices offer way out for poor resource farmers in the tropics to bring positive
changes in socio-economic set up as well as environmental benefits under a moderate canopy
shade.
1.6 Global forest resources
Forests cover about 30 percent of the Earth’s land area. According to an assessment,
total forest area in the world is estimated to be over 4 billion hectares, equivalent to 0.6 ha of
forest per capita on an average basis which is mostly unevenly distributed. The five most
forest-rich countries (Russian Federation, Brazil, Canada, USA and China) occupy about
53% of the area whereas; 64 countries with a combined population of 2 billion people have
forest area which is not more than 10% of their state boundaries. In Asia, different countries
including India, Japan, Sri Lanka and Korea have forest area ranging from 24.2 to 90.4% of
their landmass (FAO, 2010).
At all spatial scales, from local to global, trees and forests play a critical role in
human livelihoods, as well as in ecosystem functioning and health. In many local
communities worldwide, people have a daily dependence on forests, engaging in fuelwood-
gathering, the harvesting of wood and non-wood forest products, and community-based
forest management. Forests also provide wood for a variety of commercial purposes, habitat
for more than half the world’s terrestrial species; regulate supply of clean water, and other
ecosystem services.
In post-industrialization era, forests have become vital and indispensable for human
well-being, economic development and ecosystem health. For example, land-cover and land-
use changes have potentially affected regional and global climates by emitting or
7
sequestering carbon (Pan et al., 2011) and by altering the overall reflectance properties of the
Earth’s surface (Feddema et al., 2005; Avissar and Werth, 2005).
1.7 Forest sector situation in Pakistan
Pakistan is a forest deficient country having meagre forest resources as 5% area of the
country is under forest cover and per capita forest area is less than 0.03 ha as compared to
world average of 1 ha. The area covered by forests in Pakistan is one of the lowest in the
world, especially within the context of South Asia. The forest resources of Pakistan are
deteriorating both qualitatively and quantitatively because of increasing population and
urbanization. Most of the forest area is concentrated in the northern part of the country.
Khyber Pakhtunkhaw (KPK), Northern Areas and Azad Jammu and Kashmir (AJK)
comprises coniferous and scrub forests. Southern part has less forest due to arid and semi-
arid climate and having logging and grazing pressure. It has been estimated that the country
experiences the highest deforestation rate (1.1% annually). It is evident from the given facts
that it a forest-deficit country facing acute shortage of timber, fuel wood and forage. It is
becoming increasingly difficult to meet wood and wood products demands for the growing
population of the country. Moreover, degradation of forests in the form of soil erosion,
degradation of watersheds, loss of biological diversity, climatic changes and reduction in
economic contribution had led to insalubrious state of affairs in the country.
According to the Forestry Sector Master Plan (FSMP) 1992, natural forests accounted
for 4.2 million ha (4.8%) irrigated plantations occupied 103,000 ha (0.12 %) and rangelands
covered 28.5 million ha (32.4 %) out of the total land area of 88 million ha (879,800 km2).
During financial year 2011-12, forests have contributed 92,000 m3 of timber and 262,000 m3
of firewood to the country as compared to 91,000 m3 timbers and 261,000 m3 firewood in
2009-10. (Anonymous, 2012).
Economist and ecologists suggest that a country must have at least 25% of its
geographical area under forest cover for balanced economic development and ecological
equilibrium. However, achievement of this task is difficult rather impossible due to low land
availability and other mandatory resources (financial, water and human).
8
The planners, foresters and scientists have now a challenging task to manage the
natural resources for saving the society from disaster. In order to overcome the pressure on
existing forests and to utilize natural resources (light, moisture and nutrients) for maximum
biomass production and for other tangible and intangible advantages, growing trees on salt-
affected lands has become indispensable (Nadagoudar, 1986).
1.8 Justification for the present project
Agroforestry systems are capable to serve as alternative cropping system in degraded
salt-affected ecologies by ensuring higher biomass production of diversified nature,
improved environment through rehabilitation and greater economic returns. In the past, these
systems have been strongly recommended as a sustainable form of land use to provide
optimum levels of food production, supply of firewood and cash benefits by maintaining soil
fertility (Heuvelop et al., 1988; Palm, 1995). However, it must be realized that compatibility
among different components of agroforestry systems is of prime importance for achieving
higher productivity. Moreover, proper integrated nutrient management may further enhance
productivity of the systems. So, there is a dire need to determine technology packages for
intercropping related to compatibility of arable crops, grasses, forages for sustainability of
agroforestry systems.
As described earlier, Pakistan is presently undergoing large-scale deforestation, rapid
and continuous increase in forest land conversion to land cultivation, as a consequence of
population influx. Therefore, the need to adopt and establish sustainable agroforestry systems
in salt-affected landscapes cannot be overemphasized.
In order to design, establish and manage sustainable agroforestry systems, scientific
information regarding site specification, compatibility of tree species and social needs of
local communities are mandatory. Inauspiciously, data based on critical experimental studies
on compatibility of various crops, grasses with woody perennials (agroforestry systems),
their biomass production potentials, fertility dynamics and ecological/economic
considerations have not been reported extensively (Kang et al., 1990, Salazar et al., 1993).
As a matter of fact, there exists no or very rare reliable data on agroforestry practices for salt-
affected soils, particularly in Pakistan.
9
Keeping in view prime significance of tree-based alley cropping agroforestry systems
for economical utilization of salt-affected soils, studies on alley cropping systems comprising
of woody perennials (Acacia nilotica L. and Eucalyptus camaldulensis Dehnh.) and
understorey non-woody components (wheat, para grass) were considered imperative. Salt-
affected soils are generally deficient in nutrient base for plant growth; application of soil
amendments in the form of fertilizer, gypsum and farm yard manure alone and in
combination may have positive effects on the productivity of the systems. Such studies may
assist for generating valuable information for development of practicable tree-based alley
cropping systems for salt-affected lands. It may also enhance productivity by enormous
acceptability by the farming communities on regional scale.
Taking all these specifics into consideration and looking into the prospects of
agroforestry systems for development of marginal salt-affected lands in due course of time,
present studies were carried out with following objectives.
1. To study the compatibility and quantify growth/biomass production of Acacia
nilotica, Eucalyptus camaldulensis, wheat and para grass based alley cropping
systems in saline environments.
2. To determine relative effect of different soil amendments on biomass production of
wheat and para grass with Acacia and Eucalyptus-based alley cropping agroforestry
systems.
3. To monitor effect of various soil amendments on the soil characteristics involving
different tree-understorey species combinations in alley cropping agroforestry
systems.
10
Chapter 2
REVIEW OF LITERATURE
2.1 Intercropping as a customary farming practice and present scenario
Intercropping -the agricultural practice of cultivating two or more crops in the same
piece of land at the same time is an old traditional practice which aims to match efficiently
crop demands to the available growth potential and labor. Theophrastus (about 300 B.C.)
observed that different forms of intercropping systems were in practice in ancient Greece as
crops like wheat, barley, and certain pulses were frequently integrated with vines and
olives (Papanastasis et al., 2004). At present, intercropping is a well-recognized farming
practice which has been employed on about 12 million ha in South Asia (Woodhead et al.,
1994). It is estimated that different intercropping practices contribute 15-20% of the world’s
food supplies especially in tropical parts of the world (Altieri, 1999). Farmers in Latin
America, cultivate about 70-90% of beans with crops like maize, potatoes etc., whereas
maize is intercropped on 60% area of maize-growing zones (Francis, 1986). In temperate
regions, these practices are getting much consideration as a means of efficient forage
production (Anil et al., 1998; Lithourgidis et al., 2006) and for higher economic gains
(McCrown et al., 1988).
2.2 Biomass productivity status in different cropping systems
Present-day agriculture has brought substantial improvement in productivity of food
stuff in world’s farming systems to realize the requirements of fast growing human
population. It is principally based on cultivation of restricted number of plants (crops) i.e.,
adoption of monoculture pattern of farming (Vandermeer et al., 1988). However, this
improvement in productivity is at the cost of loss of natural plant biodiversity in agro-
ecosystems and sustainability of farming system (Lichtfouse et al., 2009).
11
Higher biomass productivity integrated with improved biodiversity and sustainability
of resources may be achieved by adopting appropriate practicable intercropping systems i.e.,
cultivation of two or more crops at the same time in the same field. Such systems make
efficient use of solar radiation and other available growth resources leading to higher
biomass productivity by ensuring ecological and economic sustainability. The success of
these systems depends on interactions between the component species, management
practices and environmental factors. It is revealed that higher biomass productivity,
conserved biodiversity and maintained sustainability in agro-ecosystems can be achieved
through adopting diverse intercropping systems (Malezieux et al., 2009).
2.3 Two facet effect of intercropping systems on biomass production
2.3.1 Enhanced biomass production in intercropping systems
Ganwar and Karla (1981) stated that crop growth rate (CGR) of maize intercropped
with chick pea (green and black) and cowpea in rain-fed conditions was higher than maize
grown alone whereas Lima (2000) reported that yield of intercropped maize increased by
18% compared with sole crop whereas; yield of cowpeas decreased by 5%. Araujo (1986)
concluded that net assimilation rate (NAR) of maize was higher in intercropping systems
than in monoculture.
Choubey et al. (1997) studied the effect of planting pattern on forage production of
teosinte and cowpea intercropping system and found that there was 31% and 40% increase in
green forage and dry matter yields, respectively, grown in 2:1 teosinte+cowpea pattern over
sole teosinte. Parlawar et al. (1998) reported that growing sorghum, pigeonpeas, soybeans
and cotton in intercropping systems increased total production and income compared with
monocultures. The highest net return was achieved by 1:2 pigeon pea: soybean intercropping
system.
Karikari et al. (1999) reported that groundnut+sorghum was highly productive with a
yield advantage of 67% followed by groundnut + maize with 9% yield. In another study,
sorghum-cowpea intercropping system reduced run-off by 20 to 30% compared to sorghum
monoculture and grain yield of intercropped plots was doubled (Zougmore et al., 2000).
12
Mpairwe et al. (2002) reported that cereal + forage legume intercropping significantly
yielded more (27%) fodder dry matter [DM] than sole cereal cropping (10.5 vs 7.2 t ha-1).
Fodder dry matter yield of maize + lablab intercrop was about 53% higher than in sole maize.
Fodder dry matter production in wheat + clover intercrop was 1.2 times (21%) higher than
sole wheat crop. Fodder dry matter yield gains in the intercrop averaged 34% for maize-
lablab, 39% for sorghum + lablab and 37% for wheat + clover. Chirwa et al. (2003)
concluded that higher production may be obtained by intercropping maize with pigeon pea
(Cajanus cajan L.) and gliricidia as compared to sole cropping.
Iqbal et al. (2006) concluded that maize-cowpea intercropping seemed well matched
as it yielded significantly higher than clusterbean (Cyamopsis tetragonoibous L.) and rice
bean (Vigna mungo L.) sole cropping.
Mohammad (2013) described that intercropping of alfalfa with cereals crops (oats,
barley, and maize) was 2-3 times more productive and superior in quality than the sole crops
in northen areas of Pakistan. The quality of forage produced was also superior to the sole
cereal crops of oats, barley, and maize.
2.3.2 Reduced biomass production in intercropping systems
In contrast to synergistic agroforestry studies, mismatched intercropping systems may
cause reduction in biomass productivity as documented by various researchers.
Madhavan et al. (1986) stated that cumulative growth rate (CGR) of sorghum-
pigeonpea intercropping system was less compared to their sole cropping whereas
decrease in leaf area index (LAI) was observed in sorghum–pigeonpea intercropping system.
Subramanian and Venkateswarlu (1989) indicated that net assimilation ratio (NAR) and leaf
area index (LAI) of each associated crop such as clusterbean, black gram and sorghum
decreased significantly in sorghum, castor + cluster bean and sorghum+ black gram or
pigeon pea intercropping system than their sole cropping. Jorgensen and Moller (2000)
reported about intercropping of typhoon (Brassica campestris var. rapa) with forage maize
and concluded that intercropping resulted in lower maize canopy with large leaves and
thereby reduced the forage yield.
13
Singh and Jadhav (2003) concluded that sole sorghum produced significantly more
fodder than sorghum intercropped with pigeonpea and groundnut. Thwala and Ossom (2004)
found that highest yield was achieved from sole maize compared to its combination with
groundnut and soybean and similar results were noticed in case of sole groundnut. Crop
competition was possibly the main reason for reduction in yields.
Khan et al (2010) described that different intercropping treatments had affected yield
and yield traits of mungbean when grown with maize. Highest biological yield (1654 kg ha-1)
besides grain yield (525kg ha-1) of mungbean was noted in plots where sole mungbean was
grown as compared to intercropping treatments with maize. In conclusion, mungbean (grown
singly) performed well regarding yield and yield components as compared to intercropping.
2.4 Biomass productivity in agroforestry systems
In early 1970s, International Institute of Tropical Agriculture (IITA) addressed
research activities to evaluate potential of woody species capable of growing in association
with food crops in marginal land use systems. The inspiring results of these trials led to the
development of alley farming in the early 1980s as agroforestry system which had distinctive
benefits of higher productivity and sustainability at small-scale farming systems (Kang et al.,
1990). Various scientists have reported about the performance of agroforestry systems from
time to time.
2.4.1 Enhanced biomass productivity in agroforestry systems
2.4.1.1 Enhanced biomass productivity in agrisilviculture systems
Singh et al. (1997) conducted a number of trials on a moderate alkali soil in Karnal,
India involving tree species (Populus deltoides, Acacia nilotica and Eucalyptus
camaldulensis) and crops (rice, wheat, berseem, cowpea, pigeon pea, sorghum, mustard,
berseem and turmeric) grown in sole and intercropping designs with different crop rotation
patterns. Results showed that P. deltoides and E. camaldulensis gained maximum woody
biomass when intercropped with rice whereas Acacia gained maximum growth when grown
in the absence of intercrops. Soil improvement w.r.t. various properties followed the order:
Acacia-based system, >Populus>Eucalyptus>sole crops. The value cost ratio was highest
14
(2.28) in P. deltoides based system and minimum (1.86) in Acacia based system. Therefore,
it was concluded that growing of trees in association with crops is better land use option in
terms of productivity, maintenance of soil conditions and economics.
Mantang and Haishui (1998) described that intercropping of pine apple in Eucalyptus
plantations led to two times more buildup of timber volume of woody tree as compared to
sole Eucalypytus stand.
Dhyani and Tripathi (1999) described intercropping had positive effects on tree
growth parameter as compared to sole tree plantations due to fertilizer application, land
management operations and improved tree-crop management in tree based intercropping
systems. He established these conclusions after conducting various trials on agrisilvicultural
systems based on trees including alder (Alnus nepalensis), albizzia (Paraserianthes
falcataria) and chery (Prunus cerasoides) for a period of 7 years.
McGraw (2008) conducted field trials for 03 consecutive years to grow alfalfa with
black walnut trees (Juglans nigra L.) in alley cropping design and in open field. The walnut
trees were 20 years old and planted in rows which were 12.2 and 24.4 m apart. Data
regarding growth parameters of alfalfa were recoded from two points; beneath the tree
canopy and center of alley. It was concluded from the data that alfalfa tended to mature
earlier in open field and wide alley centers as compared to underneath the canopy of both
alleys and the narrow alley centers. Similarly, yield was considerably reduced and maturity
was delayed in narrow spacing alleys (12.2 m) as compared to wider alleys (24.4 m apart).
Shapol and Adam (2008) established an alley cropping system in Sudan to study
impact of altered microclimate in 6-m wide alleys shaped by Acacia ampliceps and A.
stenophylla on growth and yield of understorey component crops i.e., groundnut and sesame.
Due to modified microclimatic conditions in the alleys, the yield of both the crops in alleys
was significantly different from respective control. Results showed that yield of groundnut
increased about 37.7 and 19.6 % in alleys of A.stesnophylla and A.ampliceps, respectively. In
contrast, yield of sesame improved with A. stenophylla-alley (+40.3%), while it reduced with
A. ampliceps-alley (-51.5%). Major contributing factor for reduction or increase in yield of
understorey crops was due to competition for light.
15
Predo and Francisco (2008) employed a bio economic modeling approach to analyze
the productivity, profitability and sustainability of unconventional cropping systems in the
degraded grasslands in Philippines. Results showed that tree-based land use systems had
significantly higher financial profitability and environmental benefits due to higher carbon
sequestration, controlled soil erosion, and sustained soil nutrients availability. Similarly, risk
analysis indicated that timber-based systems gained the highest net present value (NPV).
Hadgu et al. (2009) described about field trials conducted at regional scale to assess
barley crop productivity in Faidherbia albida-based cropping system in Ethiopia. He found
that barley yield and soil fertility improved when field locations were nearer to a F. albida
trunk. However, barley yield and fertility decreased in F. albida + E. camaldulensis land use
system as spacing from tree trunk decreased.
Das et al. (2011) described about a field trial conducted to select suitable intercrops
among turmeric, ginger and arbi to be grown in alleys of tree rows of aonla (Emblica
officinalis G.) planted at 6×6 m spacing. Results of these trials showed that production of
fruit considerably increased as it was maximum in association with turmeric (13.3 t ha -1)
followed by arbi (11.7 t ha-1). Conversely, reduction in intercrop yield followed the order:
turmeric 7.5–12.0%, ginger 12.2–19.3% and arbi 15.7–25.3% as compared to yield of the
crops grown in open field (full sunlight). Economic analysis of these alley cropping systems
w.r.t. value cost ratio (VCR) shown that aonla + turmeric gave higher value (6.29), aonla +
ginger (3.44) and aonla + arbi (3.20).
Tsonkova (2012) endorsed that alley cropping systems which integrate strips of short
rotation coppices into conventional agricultural fields had received greater attention in
temperate zones to produce higher biomass while supporting farmers to diversify their
marketable goods. Moreover, these systems have additional benefits like improvement of soil
fertility, increase in carbon sequestration, and optimization in utilization of available
environmental resources.
16
2.4.1.2 Enhanced biomass productivity in silvipastoral systems
Radhakrishnan et al. (1991) observed that herbage yield of patchouli (Pogostemon
patchouli Pellet.) was significantly higher at various intensities of shade as compared to open
field. Herbage yield under open condition (2027 kg ha-1) was low as it was 3578 kg ha-1
under 25% and 4243 kg ha-1 under 50% shade, respectively. Similarly, the highest oil yield
was recorded from the plant under 50% shade (173 kg ha-1) followed by 25% shade (118 kg
ha-1) and the least from the open condition (75.8 kg ha-1).
Mohsin et al. (1996) reported about performance of alley cropping systems
comprising of Populus deltoides, mint and Cymbopogon spp., where biomass of trees and
understorey components were higher in intercropped trees as compared to sole tree stand.
Bolivar et al. (1999) reported that Acacia mangium-Brachiaria humidicola based
systems (density of 240 tree ha-1) increased dry matter production of grass (1834 vs 2562 kg
ha-1 yr-1) with improved crude protein contents (C. P.) i.e., 3.2% vs 4.6%. Mochiutti and
Lima (2000) affirmed that Brachiaria brizantha produced 3550 kg of DM ha-1 yr-1 whereas
crude protein contents of Andropogon gayanus improved under moderate shade (density 416
trees ha-1) of Sclerolobium paniculatum.
Aquino et al. (2004) determined that B. decumbens maintained forage productivity
under trees shadow of A. mangium, A. auriculiforimis and Albizia guachepele in Brazil
whereas, Alvim et al. (2004) reported that B. brizantha had a production of 1692, 3616 and
2547 kg dry matter ha-1, under a tree cover of 12%, 22% and 30%, respectively. In case of
silvoarable systems, Samsuzzaman et al. (2002) observed that intercropping of A. nilotica
with wheat and rice lowered yield reduction of intercrops with proper tree-crop management.
Muniram et al. (1999) conducted a field research trial to workout feasibility of
intercropping patchouli with papaya and found that intercropping improved herb yield by
91%, oil contents by 76% and quality of oil by 8-11% over its sole cropping system.
Singh (2003) conducted trials to study the effect of coconut and casuarina shade on
growth, herbage and oil yield of palmarosa and lemon grass. Results showed that coconut
plantation affected herbage and oil yield upto 0-4 meter distance from plants beyond which
17
there was no effect on yields. Herbage yield of palmarosa and lemon grass was affected by
123% and 86% and oil yield by 136% and 86% respectively. However, oil contents and oil
quality were not influenced by plantation shade.
Bhatt et al. (2005) estimated biomass productivity of trees, shrubs and herbs in
differentially managed forests and established its relationship with light interception pattern
at different canopy layers. The results showed that tree biomass productivity decreased and
herb productivity increased with increasing the light gap. Biomass productivity of herbs
attained maximum level at light gap of 40–60% as compared to plots having no trees or
100% light gap. These studies showed that partial shading enhanced herb layer productivity.
Therefore, agroforestry has the capability to enhance total biomass productivity in
agroecosystems.
Singh et al. (2008) reported diversity-productivity relationship of understorey
vegetation under Acacia nilotica, Azadirachta indica, Prosopis cineraria and P. juliflora for
utilization of positive interactions in agroforestry and silvopastoral systems. Results showed
that about 83-88% reduction occurred in light factor i.e., photosynthetically active radiation
(PAR) and 9-22% reduction in soil water under tree canopy as compared to control. Average
population and community biomass variables were 3.1 and 2.9 times higher under P.
cineraria than in the control plots, whereas these parameters were lowest under A. nilotica
based systems. Population diversity characteristics like species richness and evenness were
highest under A. nilotica and P. juliflora, respectively, whereas diversity index and
species dominance were highest under A. indica and P. cineraria, respectively. This
study also specified correlation between species richness and community biomass so as to
elaborate interspecies competition. Similarly, results also showed that enhanced productivity
of pastureland in dry areas may be achieved through tree integration with suitable grasses. P.
cineraria was found capable for supporting highest biomass under canopy.
Hadgu et al. (2009) described about field trials conducted at regional scale to assess
barley crop productivity in Faidherbia albida-based cropping system in Ethiopia. He found
that barley yield and soil fertility improved when field locations were nearer to F. albida tree.
However, barley yield and fertility decreased in F. albida + E. camaldulensis land use system
as spacing from tree trunk decreased.
18
2.4.2 Reduced biomass productivity in agroforestry systems
2.4.2.1 Reduced biomass productivity in agrisilviculture systems
It is common practice in Indo-Pak sub-continent that farmers grow trees on their
farmlands in linear and block formation. In block arrangement, mostly intercropping is done
with different crops like sugar cane, wheat, potato, turmeric, vegetables etc. during the initial
growth of trees (2-3 years). Later on, crop yields are significantly declined and farmers
discontinue cultivating crops within tree blocks (Hussain et al., 1999). In fact, above and
below ground interactions define resource sharing patterns among different tree and tree
components in an agroforestry system and thus control productivity of the system Gillespie
et al., 2000). In order to get optimal benefits from tree based intercropping systems, farmers
should rightly select different components of the systems (compatible tree and crop species)
as well as make decision about planting density and other management practices. The
customary practices regarding tree based alley cropping systems have been documented by
various researchers regarding different aspects.
Sharma et al. (1994) appraised the effects of growing pearl millet and cluster bean in
association with A. tortilis and Zizyphus rotundifolia for four years. Growth of trees (height,
dbh) and crops (grain and straw yield) were higher in control (sole tree/sole crop) while they
decreased in intercropping systems. However, soil organic matter contents increased in the
order: cluster bean>pearl millet and Z. rotundifolia>A. tortilis.
Sharma et al. (1996) described that growth and yield of wheat and rice were
negatively affected by Dalbergia sissoo tree lines on northern side (under full shade). The
reduction effect, in case of rice, was more evident on yield components (plant density,
number of tillers per plant, grain and straw yields and total biomass) of paddy crop up to 15
m distance from tree line when compared to control. The effect was more pronounced on all
parameters. However, in case of wheat, this effect was confined mainly within the canopy
limits.
Hocking et al. (1996) monitored yield performance of rice and wheat grown in
association with five different tree species in Bangladesh. Results showed that, in general,
there was a yield reduction trend for both the crops. The yield reduction variation ranged
19
from 16% under A. catechu (light-canopied tree species) to about 40% under Artocarpus
heterophyllus and Mangifera indica (dense-canopied tree species). Yield reduction was
noticed more prominently in dry winter season as compared to wet (monsoon) season. In
monsoon season, yield reduction may be attributed mainly to shade factor as there was no
limitation regarding moisture availability due to abundant rainfall. Regarding yield
components, it was also observed that straw yield was less reduced as compared to grain
yield.
Bisaria et al. (1999) revealed that growth of Hardwickia binata trees was lower where
trees were growing in association with intercrops (Brassica campestris and Glycine max) as
compared to sole tree crop possibly due to allelopathic interaction of intercrops with H.
binata.
Andrade and Ibrahim (2001) stated that forage yield of Brachiaria decumbens, B.
brizantha, and Panicum maximum reduced up to 23%, 30% and 39% , respectively, under
natural shadow of Acacia mangium and Eucalyptus deglupta (density: 370 trees ha-1).
Peri et al. (2002) reported that trees grown as sole tree plantation had higher growth
in volume i.e., 34 and 29% as compared to the trees grown in association with lucerne
(Medicago sativa) and cocksfoot (Dactylis glomerata), respectively.
Samsuzzaman et al. (2002) described that grain yield of wheat and rice reduced
significantly in Acacia nilotica-based alley cropping systems than in the open field because
of development of competitive interface between tree and crop components. Rice was found
more affected than wheat due to shade effect.
Prasad and Srinivas (2012) reported that tree-based systems with short rotation
species have the potential to sequester carbon as a mitigation strategy for adverse effects
associated with climate change due to elevated concentration of green house gases. The
estimated carbon stock of Leucaena-based agroforestry system was about 62 t ha-1 whereas,
in case of Eucalyptus-based agroforestry system, it was about 34 t ha-1 during 4 years rotation
in degraded salt-affected lands. Biomass production and carbon accumulation were relatively
higher in farm forestry systems as compared to sole tree plantation.
20
Dufour et al. (2012) conducted a trial to monitor the productivity of durum wheat in
walnut (Juglans nigra L.) based agroforestry system and under artificial shade conditions and
applied statistical model (STICS) to simulate the crop productivity in different shades
conditions and full sunlight. Result of this study showed that yield of wheat was decreased up
to 50% due to shade factor (light reduction: 31%). Other yield components including number
of grains spike-1 (35% reduction), kernel weight (16% reduction) were also affected.
However, protein contents were enhanced in shaded conditions (about 38% in artificial
conditions).
2.4.2.2 Reduced biomass productivity in silvipastoral systems
Kamala et al. (1990) described about evaluating biomass production of Mentha
species intercropped with poplar and found that herbage and oil yield reduced about 10-26
and 8-24%, respectively, in 2nd and 3rd year of growth due to increased shade effect which
was not significant in 1st year.
Sharma et al. (1996) described that growth and yield of wheat and rice were
negatively affected by Dalbergia sissoo tree lines on northern side (under full shade). The
reduction effect, in case of rice, was more evident on yield components (plant density,
number of tillers per plant, grain and straw yields and total biomass) of paddy crop up to 15
m distance from tree line when compared to control. The effect was more pronounced on all
parameters. However, in case of wheat, this effect was confined mainly within the canopy
limits.
Acciaresi et al. (1994) reported about findings of a trial where a mixture pasture of
Cynodon dactylon, Paspalum dilatatum, Lolium multiflorum and Bromus unioloides, was
intercropped using Populus deltoides Marsh. (Planting density: 625, 416, 312, 250 and no
trees ha-1). The results indicated that higher biomass production (dry matter: 8 tons ha -1)
was achieved at planting density of 250 trees ha-1; however, there was no statistical
differences in grass production when compared with the treatments in open field (without
trees).
21
Vijayalalitha and Lada (1996) found that there was a lot of variation in assimilation
ability of different genotypes of patchouli under open and shade regimes. Some genotypes
had high, some low and some behaved neutral to light regimes. Overall, assimilatory capacity
in all the genotypes got reduced under shade conditions.
Kaul et al. (1997) found that herb and oil yield of various cultivars of geranium
declined significantly when grown under shade of trees including lemon scented gum,
gulmohar, peltoforum, and parkinsonia in contrast to plants grown in open field (without
shade) conditions. Bisaria et al. (1999) concluded that growth of trees (Hardwickia binata)
was lower where trees were growing in association with intercrops (Brassica campestris and
Glycine max) as compared to sole tree crop possibly due to allelopathic interaction of
intercrops with H. binata.
2.5 Light factor in agroforestry systems
The commonest impact of trees on vegetation growing underneath the canopy is to
reduce the biomass production and yield of crops (Mordelet and Menaut, 1995). It is, because
reduced irradiance has a substantial impact on plant productivity, at the ecosystem level.
Accessibility to light is a foremost ecological aspect prompting plant growth and survival.
Plants respond different ways in changing light intensities depending on their genetic
makeup, capability for adaptation and phenotypic acclimation (Lambers et al., 1998).
Ealrlier investigations carried out in various agroforestry systems with the objective
to pin down the cause of decline in crop yields show that competition for light is the major
factor. Chirko et al. (1996) reported that maize crop being sensitive to shading due to C-4
photosynthetic pathway suffers higher yield loss in agroforestry systems. Gillespie et al.
(2000) reported that maize crop grown in an alley cropping system with black walnut
(Juglans nigra L.) and red oak (Quercus rubra L.) suffered a yield decline of 50% in USA.
The effect of incident photosynthetically active radiation (PAR) on crop yield may be
minimized through canopy management as light may become a major limiting factor for
crops growing under denser canopies.
22
Serra et al. (2001) reported that in coconut (Cocos nucifera) based agroforestry
systems, growth and yield components of annual and perennial intercrops were highly
influenced by shading as photosynthetically active radiation (PAR) is a limiting factor in
such systems.
Muchiri et al. (2002) stated that maize crop production was not profitable enterprise
under tree cover (Grevillea robusta) as if we manage the canopy for profitable maize
production, wood production on the other hand is reduced by 57% in even-aged forestry. In
these studies, models were developed to know the influence of trees on maize yield, to
standardize the density and tree cover size distribution in alley cropping systems. The models
indicated that maize yields considerably decreased due to high competition by trees at higher
densities. Preferable stocking rate was found to be about 200 tree ha-1.
Friday and Fownes (2002) described that success of an agroforestry system depends
mainly on minimizing tree-crop antagonism/competition. In a field trial, they concluded that
light intercepted by maize growing in alley crop design was about half as compared to
intercepted by the crop growing in sole pattern. Light interception in agroforestry systems
affects the growth and development of understorey herbaceous vegetation in various ways
(Dodd et al. 2005). Generally, herbage production decreases as light intensity decreases, due
to reduced photosynthesis and modification of leaf and tiller anatomy (Devkota and Kemp
1999).
Franck and Vaast (2009) examined how coffee plants adapted to different shade
intensities by recoding spot measurements of coffee grown under varying levels of solar
irradiance at Costa Rica. Production performance at a range of light levels (from darkness to
full sun) was assessed using photosynthetic rates and stomatal conductance. A negative
relationship was found between leaf light exposure duration and quantum use efficiency
whereas a positive relationship was observed between leaf light exposure duration and
maximum photosynthesis rate. In essence, tree-crop competition significantly depends on
light factor in agroforestry systems.
23
2.6 Effect of saline water on soil properties
Higher concentration of salts seriously disturbs physical and chemical properties of
the soil and made it unfavorable for crop growth (Qadir et al., 2000). Soil irrigation with low
quality water causes soils salinization (Rhoades et al., 1992) and soil deterioration (Chaudhry
et al., 1983). Use of brackish irrigation water increases soil pH (Alawi et al., 1980 and
Mostafa et al., 1992), EC (El-Boraie, 1997), SAR (Zein El-Abedine et al., 2004), soluble
Ca2+, Mg2+, K+ and Na+ (El-Boraie, 1997) and soluble anions (Abo El-Defan, 1990). The
most severe toxic effect of Na+ ions in irrigation water on the physical properties of soils is
described as decrease in hydraulic conductivity (HC) of soil. These adversarial effects are
further intensified by the presence of CO32- and HCO3
- ions in irrigation water leading to
higher SAR.
Higher level of exchangeable sodium undesirably affects structural changes of soil
matrix mainly by two mechanisms (i) clay swelling and (ii) soil particle dispersion. Both the
mechanisms are strongly interrelated to decrease HC of soils. It may be presumed from the
Diffuse Double Layer Theory (Bohn el al.,1985; Gapon, 1933) that both swelling and
dispersion of particles increases as the concentration of electrolyte in soil solution decreases
and Na+ to Ca+ ratio of the soil solution is increased (Oster et al., 1980). In a long-term study,
Bethune and Batey (2002) found that continuous use of saline-sodic water (EC=2.5-4.5 dS m-
1 SAR=12.5- 17.1) on a normal loam soil for 10 consecutive years resulted in high level of
soil sodicity (ESP up to 45%). Kazman et al. (1983) found that chemical dispersion is
restricted in calcareous soils or when a high electrolyte concentration is present in the
irrigation water applied. The intensity of chemical dispersion increased sharply with an
increase in soil sodicity.
Sharma and Dubey (1988) also supported the above findings that irrigation with
saline water increased salinity and alkalinity (ESP) and decreased crop yields. The upper soil
layer was more severely affected than the lower layers. The salt content of irrigated soils is
likely to increase, particularly where drainage is poor, resulting in marked yield reductions.
Thus, the use of the groundwater should be reduced and that irrigation should be adapted to
the drainage capacity of the soils (Soderstrom and Soderstrom, 1989).
24
Bajwa et al. (1993) observed that irrespective of the irrigation intervals, sustained use
of sodic and saline-sodic waters increased pH, electrical conductivity and exchangeable
sodium percentage of the soil and significantly decreased crop yields. Application of gypsum
decreased ESP and significantly improved crop yields. There were no significant beneficial
effects of increasing the frequency of sodic and saline sodic irrigation, both with and without
applied gypsum, on the yields of wheat and millet crops grown during winter and monsoon
seasons, respectively.
Abu-Awwad (1995) also stated that increasing irrigation water salinity resulted in a
significant increase in sweet corn root zone salinity. Highest salt concentration in the root
zone occurred when the amount of water applied was close to the crop evapotranspiration.
Salt accumulation was minimum close to the trickle line and increased with both vertical and
horizontal distance reaching a maximum at the soil surface and at the edges of the wetted
area between trickle lines. Soil water availability decreased with increasing salinity of
irrigation water (Ashraf and Saeed, 2006).). They found that saline groundwater increases
salinity in root zone therefore, appropriate amount of pumped water should be applied. Salt
accumulation in root zone in alternate furrow field was less than that in regular furrow field.
Rajesh and Bajwa (1997) suggested that irrigation with saline water alone
significantly increased salt build up in soil and decreased growth of plants of all three crops.
Inclusion of canal water for irrigation in the saline water irrigation system decreased salt
build up in soil and improved plant growth. Use of canal water in conjunction with saline
waters having high or low SAR under low or high EC resulted in appreciably lower buildup
of ESP in soil than that observed under saline irrigation alone.
Shainberg et al. (2002) reported that irrigation with saline water may introduce
sodium into the exchange complex of soils. Exchangeable sodium deteriorates soils structure
and permeability. The susceptibility of soils to sodicity depends on (1) soil permanent
properties (such as texture and mineralogy) and (2) time dependent variables such as
cultivation (and time since cultivation), irrigation methods and wetting rates. Mao et al.
(2003) also suggested that irrigation with brackish water resulted to rapid accumulation of
25
salts, notably in the upper 80 cm soil layer. Maximum electrical conductivity (EC) in the 20-
40 cm soil layer exceeded 20 mS/cm. Salts were leached from the 150 cm layer during the
wet season. All the salts in the 80 cm soil layer of the sandy loam soil were leached with total
precipitation of 550 mm and additional 250 mm irrigation water. The average yield of winter
wheat and summer maize under brackish water irrigation was 91 and 92%, respectively, of
maximum recorded values, but only 67 and 89% in non-irrigated treatments. The yield of
winter wheat after 3 years of brackish water irrigation was approximately 92% of maximum
value. Results confirmed that brackish water irrigation was economically attractive to
farmers for a short term. Ecological hazard may occur in long term use of the water. An
average EC lower than 8 mS/cm in the 20-60 cm soil had no significant effect on the yield of
summer maize. Maize yield would significantly decrease if the EC was 10-15 dS m-1 at dry
year, while winter wheat would decrease by 10%.
2.7 Effect of farm yard manure under saline conditions
Farm yard manures (FYM) improves soil properties such as water holding capacity
and soil aeration (Schoenau et al., 2004), regulate soil pH, decreases harmful effect of salts,
improve nutrient availability (Singh et al., 2000), nutrient recycling (Cook, 1982) and serve
as a source of plant nutrients. Addition of FYM has been shown to increase maize green
fodder yield by 25% (Mehta et al., 1994). The application of mulched straw, gypsum, and
phosphogypsum (PM) especially in combination with manure can to some extent compensate
for the unfavorable effect of the saline irrigation (Anikanova, 1998). Further, organic waste
application decreased soil bulk density and increased total porosity. Water holding pores and
fine capillary pores were increased with addition of organic wastes, with pronounced
increase in plots with PM. Organic matter content increased and soil pH decreased due to
addition of these organic wastes. It was concluded that the effect of waste materials on soil
properties depended on their type and rate of application (Noufal, 2005).
Lithourgidis et al. (2007) reported that corn grain and silage yields, N-P-K plant
concentration, and uptake were significantly increased by manure or inorganic fertilizer
addition relative to the control. During the 4-yr corn experiment, the amounts of available
NO3-N in the soil profile of manure plots were higher than control, but similar to both
26
inorganic fertilization treatments. Manure application maintained the amounts of soil
available NO3-N, P, and K at desirable levels, almost each year of the total 8-yr application.
However, soil organic C and Kjeldahl N remained unchanged. At the end of the experiment,
soil salinity below 30 cm was significantly increased on manure or inorganic fertilizer
addition relative to the control, but at levels acceptable for most crops. In conclusion, soil
application of liquid dairy cattle manure at a rate equivalent to the recommended inorganic
fertilization can enhance corn yield and composition and maintain soil fertility at desirable
levels, without increasing soil salinity at unacceptable levels.
2.8 Effect of salinity on nutrient elements
The findings of Irshad et al. (2004) showed that saline irrigation water has a
tremendous impact on the yield potential of crops. In saline water the roots contained the
highest Na content; Ca and Mg were higher in the leaf, whereas K and Cl were highest in the
stalk. In non-saline water, Na and Cl were highest in the root and the remaining elements
were greatest in the stalk. The K and Cl contents were significantly reduced by an increase in
the N level, whereas the reverse was true for the Ca, Mg and Na contents. An inverse
relationship was noted for the plant biomass versus both Na uptake and the Na/Ca, Na/Mg
and Na/K ratios in plants irrigated with saline water. The mineral elements, with the
exception of K, appeared to be highly correlated in the plant parts.
Kandil et al. (2003) worked on safe use of low quality water for irrigation. They
indicated that highly significant differences were found between the composition of irrigation
water used in studied area including; soluble salts, pH, sodium adsorption ratio,
macronutrients (N, P, K), micronutrients (Zn, Cu, Mn, Fe) and some heavy metals (Cd, Pb,
Co, Ni, Cr,) content. Highly significant correlations were found between the chemical
composition of irrigation water used and soil chemical properties (whole profile), which
predict the soil contamination due to irrigation with low quality water. Highly positive
significant correlations were found between organic matter, calcium carbonate and soil
salinity, available macro- and micronutrients and some available heavy metals. Soil reaction
has a highly negative significant effect. Highly significant correlations were found between
the soil content of macro-, micro-nutrients and heavy metals, and its accumulation in shoots
27
of berseem (Trifolium alexandrinum) and shoots and grains of maize. Yuncai et al. (2008)
reported that saline irrigation recorded reduction in evapotranspiration, maize growth, such
as plumule fresh weight and dry weight, and leaf fresh weight and dry weight under drought
and salinity, the application of foliar fertilization did not improve plant growth under short-
term drought or salt stress.
2.9 Integrated nutrient management in agroforestry systems
In various agroecosystems, soil fertility may decline due to numerous factors such as
leaching, soil erosion, harvesting of farm products as well as management features involved
in crop husbandry (Donovan and Casey, 1998). In agroforestry systems, huge quantities of
nutrients are removed for production of harvestable and non-harvestable entities over time
which ultimately results in decline of productivity of the land due to decline in fertility
(Kapkiyai et al., 1998; Adiel, 2004). In such situations, performance of agroforestry systems
is often less efficacious than anticipated leading the whole system to non-sustainability.
Soil fertility status in agroforestry systems may be reinstated through integrated plant
nutrient management (IPNM). It is an approach dealing with maintenance of soil fertility for
sustaining crop productivity through utilization of all possible sources of plant nutrients
(organic and inorganic) in an integrated manner appropriate to each cropping system and
farming situation within its ecological, social and economic prospects (Tandon and Roy,
2004) along with additional benefits of enhanced soil productivity, resilience of the land to
erosion and degradation, soil and agro-biodiversity and to mitigate the effect of climate
change.
2.9.1 Application of inorganic fertilizers in alley cropping systems
A considerable knowledge gaps exist regarding the breakdown of organic residues,
and interactions between mineral and organic amendments in agroforestry systems. Szott and
Kass (1993) described that fertilizer response was positive in alley cropping systems. He
concluded that systems based on annual crops (e.g., alley cropping) were less nutrient-
efficient and sustainable than systems based on perennial crops probably due to reduced
fixation and transfer of N to the crops, the tendency of trees to compete for and sequester
28
nutrients, relatively high phosphorus (P) requirements of crops and high labor cost of tree
management.
Kang et al. (1985) applied nitrogen fertilizer to maize and cowpea grown in
association with leucaena (Leucaena leucocephala L.) in alley cropping design in Nigeria.
Results showed that application of nitrogen to maize crop increased yield of maize
significantly whereas cowpea yield was not affected. Yamoah and Burleigh (1990) reported a
substantial increase in pole bean (Phaseolus vulgaris) production when phosphorus fertilizer
@ 30 and 60 kg ha-1 was applied to Sesbania sesban alley cropping systems.
Fernandes (1990) reported about fertilizer application in an alley cropping study
conducted at Yurimaguas Experimental Station in the Amazon Basin of Peru. The soil was a
fine-loamy, siliceous, isohyperthermic Typic Paleudult. Double hedgerows of Inga edulis
were established and an annual rotation of upland rice/upland rice/cowpeas provided the test
crops over several years. From the 2nd rice crop, the effects of I. edulis prunings applied as a
mulch, application of 50 kg N + 25 kg P + 20 kg K + 35 kg Ca + 16 kg Mg ha-1, and repeated
root pruning of I. edulis were investigated. Mulching significantly increased rice grain yields
only in the 2nd crop and reduced seed yields of cowpeas. Rice yields were higher in the 4 th ,
5th and 7th rice crops and the 6th cowpea crop. Hedgerow root pruning significantly
increased yields of the 5th and 7th rice crops and the 6th cowpea crop and gave non-significant
increases in other crops.
Siwa et al. (1991) stated that application of nitrogen fertilizer on yield of maiz grown
in alley cropping design with Acioa and Leucaena hedgerows increased maize grain yield in
general. Mean yield increase due to N application was highest in the control (47.2%)
followed by the sole Acioa hedgerow (25.2%) and less in hedgerows with Leucaena. Palada
et al. (1992) described that fertilizer (N 30, P 13 and K 24 kg ha−1) application increased
mean yields of Amaranthus, Celosia, okra and tomato by 325, 164, 47 and 94% in control
plots and by 36, 26, 4 and 20%, respectively in 4 m wide alley of L. leucocephala.
Sureshi and Rao (1999) stated about a trial to study the effect of nitrogen (four levels;
0, 20, 40 and 60 kg N ha–1) applied to sorghum intercropped with three nitrogen fixing trees
viz., Faidherbia albida, Acacia ferruginea and Albizia lebbeck forming 4 m wide alleys.
29
Results showed that association of tree species reduced grain and dry- fodder yields of
sorghum up to 12 to 40% as compared to sole crop. The reduction was maximum under A.
lebbeck while minimum with F. albida and moderate under A. ferruginea. Same was the
response regarding other growth parameters and yield components. Photosynthetically active
radiation (PAR) was significantly lower under tree based systems as compared to open field
conditions. The relative PAR intercepted under the trees was in the order: F. albida > A.
ferruginea > A. lebbeck. Application of 40 kg N ha–1 resulted in maximum increase in grain
and dry fodder yields over other levels. Soil moisture contents were more in sole crop
situation (open field) and at all stages of crop growth whereas it was more favorable under F.
albida than under the other tree species.
Okogun et al. (2000) described about evaluation of the effect of 0, 40 or 80 Kg N ha-1
applied to maize crop grown in alley design with Albizia lebbeck, Senna corrymbosa,
Gliricidia sepium and Leucaena leucocephala. Results showed that maize production (shoot
biomass and grain yield) was the highest in A. lebbeck alleys and the lowest in S. corrymbosa
alleys.
2.9.2 Application of organic fertilizers in alley cropping systems
Mathuva et al. (1998) described about a research trial to explore potential of
hedgerow intercropping (HI) with Leucaena leucocephala as an alternative strategy to the
use of inorganic fertilizers for improving maize yields in semiarid highlands. The study
included four treatment, sole maize with or without fertilizer; HI with prunings of L.
leucocephala hedges used as green manure or with prunings, maize stover fed to
oxen and farm yard manure. Results showed that sole maize crop responded to inorganic
fertilizer but more improvement in yield was recorded in HI, with prunings used as green
manure.
Njoka et al. (2006) stated about a trial conducted to examine fodder productivity of
napier grass (Pennisetum purpureum cv. Bana) intercropped with seca (Stylosanthes
scabra cv. Seca) and siratro (Macroptilium atropurpureum cv. Siratro). Results
showed that seca formed a better association with fodder grass for intercropping.
30
Total dry matter yield was highest during rainy seasons and declined in subsequent seasons
and was lowest during dry seasons.
Monicah Mucheru-Muna et al. (2007) carried out an experiment in Kenya to probe
the effects of application of different materials (farm yard manure, Leucaena leucocephala,
Tithonia diversifolia, Calliandra calothyrsus) and inorganic fertilizer on maize yield and soil
chemical properties. Results showed that Tithonia treatments gave the highest grain yield
(5.5 t ha−1) while the control treatment gave the lowest yield (1.5 t ha−1). Similarly, total soil
carbon and nitrogen contents were improved with application of organic residues and farm
yard manure.
Ahmed et al. (2010) stated about conducting a trial to evaluate variations in soil
properties at different levels of nitrogen in alley cropping system. Four tree species including
Leucaena leucocephala, Gliricidia sepium,Cassia siamea and Indigofera tysmanii were
applied with five levels of nitrogen (0, 25, 50, 75 and 100% plus pruned material). Results
showed that Gliricidia sepium (10.6 t ha-1) retained its superiority in growth performance
over other tree species followed by Indigofera tysmanii (10.4 t ha-1). Soil properties like total
N, available P, exchangeable K, cation exchange capacity (CEC) and organic carbon (C)
were also improved in alley cropped plots over their original values.
Ayoola and Makinde (2011) described about a field trials onducted in Nigeria to
assess the effect of application of organic-based fertilizer (OBF) and inorganic fertilizer on
the yield performance of cassava-maize intercrop. Highest maize grain yield (2.45 t ha-1) was
recorded with application of 5 t ha-1 OBF + 100 kg ha-1 NPK. Results showed that crop
yields and soil nutrient status significantly decreased with when no fertilizer was applied to
the alley cropping system.
Hulikatti and Madiwalar (2011) reported about conducting a field experiment to study
the impact of different nutrient management practices on growth and nutrient uptake in
Acacia auriculiformis. The results showed that nutrient application (FYM + NPK) had
significantly higher impact on dry biomass, number of branches, leaves and total above
31
ground parts. The uptake of N and P was recorded significantly higher due to FYM + NPK;
whereas; uptake of K was not affected.
Bernatchez et al. (2013) described about efficacy of different organic fertilizer and
gypsum (0 or 3,000 kg ha−1) on two varieties of wild leek (Allium tricoccum) viz., tricoccum
and burdickii growing under sugar maple forest stands. Results showed that fertilized plants
exhibited better growth as compared with non-fertilized plants. Ratio of belowground:
aboveground biomass also indicated that plants getting more fertilizer were able to produce
larger bulbs; however, leaf size did not differ significantly. Leaf nutrient analysis of wild leek
plants also showed that fertilizers should be applied once a year, whereas gypsum is applied
less commonly.
2.10 Alley cropping systems for salt-affected soils
Grewal and Abrol (1986) reported about field studies carried out on alkali soils to
assess the growth response of component species (Eucalyptus tereticornis, Acacia nilotica L.,
Parkinsonia aculeata L. and kallar grass Leptochloa fusca L.) of agroforestry systems to
some management practices. The tree planting was done using soil amendment (gypsum 2
kg, FYM 8 kg, N 50 g, zinc sulphate 10 g and original soil). Results showed that mean plant
height of Eucalyptus tereticornis smith; Acacia nilotica L; and Parkinsonia aculeata L. in 2
years growth period was 273 and 328, 240 and 240 cm, respectively. Same trend was
followed by other parameters of biomass accumulation during 2 year growth period. The
competition for moisture exerted by grass was more prominent in summer months. In
general, Acacia nilotica was found more promising than Eucalyptus and Parkinsonia as it
experienced low mortality and had better chemical constitution (the lowest Na:K and Na:Ca)
to tolerate adverse alkali soil environment.
Gill and Abrol (1986) described about a study conducted to assess the effect of
amendments applied to Acacia nilotica and Eucalyptus tereticornis in Karnal, India; results
showed that tree establishment aided with addition of gypsum and farm yard manure lowered
pH from 10.5 to 9.5 and electrical conductivity (EC) from 4 to 2 dS m-1 in five years.
32
Singh et al. (1997) reported about evaluation of growth behavior of mesquite
(Prosopis juliflora) as affected by planting methods and application of soil amendments
during early stages of establishment in a highly alkali soil with and without kallar grass [alley
cropping design] at Karnal, India. Results showed that after 2 years of growth period, plant
height (cm) and DBH (mm) were 319 and 15.1 with grass as compared to 405 and 20.3 in
without grass treatments. Total biomass attained in 2 years was about 3 times more where
inter-row space was not planted with grass.
Singh et al. (1995) described about trial conducted related to planting planting
techniques, for establishing mesquite plantations on highly deteriorated alkali soils was found
to use trenches (dimensions 30×30 cm); filled with mixture of original soil, gypsum @ 3 kg
and farm yard manure 8 kg plant–1. Kallar grass grown in association with mesquite gave
green forage yield of 25.3 t ha-1 in 8 cuts in a period of 26 months. Significant improvement
in soil properties was also monitored with cultivation of kallar grass as pH and EC of soil
reduced whereas; organic carbon, available nitrogen, infilteration rate and moisture storage
capacity. Thus, for over two decades, alley cropping techniques practiced over thousands of
hectares have proved successful in various agro-ecological zones for economical utilization
of marginally productive salt lands using salt tolerant plants (Acacia nilotica, Casuarina
equisetifolia, Prosopis juliflora, Tamarix articulate and Leptochloa fusca)
The most successful alley cropping system comprised of Prosopis juliflora and
Leptochloa fusca developed on an alkaline soil for fuel wood and forage production (Singh,
1996). Economic analysis of this system showed higher contribution of fiscal returns as well
as biological reclamation of salt-affected soil.
Kaur et al (2002) studied a silvopastoral system comprising of three tree species
(Acacia nilotica, Dalbergia sissoo and Prosopis juliflora) and grass species such as
Desmostachya bipinnata and Sporobolus marginatus. It was found that a significant
relationship between microbial biomass carbon and plant biomass carbon as well as the flux
of carbon in net primary productivity. Nitrogen mineralization rates were also higher in
silvopastoral systems than grasslands (without trees). Organic matter in soil was linearly
related to microbial biomass C, soil N and N mineralization rates. On the basis of
33
improvement in soil organic matter, enlarged soil microbial biomass pools and greater soil N
availability with tree + grass intercropping, they concluded that agroforestry has immense
potential for improving the fertility of highly sodic soils.
Datta and Singh (2007) recognized that in agroforestry systems based on various trees
and crops (rice, groundnut, sesamum); Acacia auriculiformis (spacing:2 m×2 m; density
2500 trees ha-1) had production potential of 635 m3 ha−2 with MAI of 2.54×10−2 m3 tree1 a−1
during rotation period of 10 years. In contrast, Eucalyptus hybrid (spacing: 3 m × 3 m;
density 1111 trees ha−2) produced timber with volume about 315 m3 ha–2 with MAI of
1.77×10−2 m3 tree− a−1. In case of crop component of the system, rice, groundnut and
sesamum were grown during initial period up to 8 years of tree establishment. In general,
there was reduction in crop productivity as compared to open space. Monitoring of soil
properties showed high nutrient availability, increase in soil organic carbon, high moisture
availability in upper surface soil, enhanced humification of soil humus and low soil
erodibility.
Mishra et al. (2010) reported about growth, biomass production and photosynthetic
pattern of Cenchrus ciliaris under canopies of Acacia tortilis (17 yr. old) in semi-arid tropical
environment. Results showed that photosynthetically active radiation (PAR) was reduced up
to 55% under fully grown canopy of A. tortilis (spacing 4x4 m) due to which relative
humidity (RH) increased whereas canopy temperature reduced up to -1.75 oC as compared to
open air temperature. Regarding growth parameters of C. ciliaris, it got higher height under
the shade of A. tortilis, whereas number of tillers and leaf area index decreased marginally
under the shade as compared to grass grown in open field. C. ciliaris growing under canopy
also accumulated higher chlorophyll a and b indicating its higher potential for shade
adaptation. Due to low availability of PAR, plant assimilatory functions such as rate of
transpiration, photosynthesis and leaf stomatal conductance decreased significantly under
tree canopies. Fresh and dry weight of C. ciliaris decreased considerably under tree canopies
as compared to open field. On average basis, C. ciliaris produced biomass (green 12.78 and
dry biomass 3.72 t ha-1) under the tree canopies of A. tortilis. In other words, dry matter yield
decreased to 38% under the tree canopies as compared to openly grown grasses.
34
Soil properties also improved in A. tortilis + C. ciliaris silvopastoral system as soil
moisture, organic carbon content and available N, P and K were found higher as compared to
open field. These characteristics may be helpful for sustainable biomass production in an
agroforestry system for a longer period. Chemical analysis of grass showed higher
accumulation of sugar, starch, nitrogen and crude protein in leaves and stem of C. ciliaris
which showed that C. ciliaris grass maintained its quality under A. tortilis-based silvopastoral
system. So it was concluded that for sustainability of the system, about 55% or more PAR is
required for sustainable production in silvopasture systems for longer period.
Narendra et al. (2011) described about the performance of forage grasses (IGFRI-7,
Coimbatore-2, Guinea grass, IGFRI-3) and Acacia auriculiformis based silvopastoral system
at Heepanalli. Among forage grass species, guinea grass produced higher fresh and dry
weight (4781 and 2732 kg ha-1, respectively) as compared to other grass species included in
the trial.
2.11 Agroforestry systems for reclamation of problem soils
Agroforestry techniques offer a great potential for reclamation of salt-affected soils.
These techniques involve planting multipurpose trees that are capable of salt tolerance and
have reclamation effect to adverse soil conditions. Several species of such trees that are of
economic value have been successfully grown in various regions affected with saline
conditions.
Ahmed (1991) reported that Acacia nilotica, Acacia tortilis, Prosopis juliflora, Butea
monosperma and Eucalyptus spp. performed well when planted in salt-affected environment.
Their survival and growth rate further improved when these plants were applied with soil
ammendments like gypsum and farmyard manure. Regarding tolerance to higher pH, Dagar
et al. (1994) observed that Acacia nilotica, Tamarix articulata, Achras japota, Casuarina
equisetifolia and Prosopis juliflora etc. could tolerate pH more than 10.0; Eucalyptus
tereticornis could tolerate pH 9.1 to 10.0 and Acacia auriculiformis, Azadirachta indica,
Melia azaderach, Populus deltoids etc. up to pH 9.0. Similarly, Yadava and Prakash (1995)
described that Termnalia arjuna, Albizzia procera, Eucalyptus hybrid and Leucaena
leucocephala were more tolerant to salinity as they survived upto ECe 12.2 dS m-1.
35
Basavaraja et al. (2011) reported about potential capabilities of Acacia nilotica to
reclaim sodic soil in central dry zone of Karnataka, India. Analysis showed that marked
reduction in saturated extract pH throughout the soil profile and ECe to a depth of 30 cm was
recorded in 10 years old plantation. Similarly, improvements were noticed in saturated
extract of Ca, Mg and K throughout the soil profile depth. In contrast, exchangeable
sodium % (ESP) and sodium adsorption ratio (SAR) concentration were drastically reduced
in the soil profile. A considerable development in organic carbon, cation exchange capacity
(CEC) and other nutrients status of sodic soil was perceived due to tree plantation stand over
a period of ten years. Canopy width and root length being important traits for bio-reclamation
of sodic soils showed highly significant and negative association with soil pHs and ESP
status while association with CEC was observed significantly positive.
2.12 Economic assessment in agroforestry systems
Economic evaluation plays an important role to assess the technology for viability
and acceptability for farming community. Kermani (1980) described about analysis of
eucalyptus + cotton based agroforestry system in Pakistan and termed it best for higher
monetary returns, while Mathur et al. (1984) reported that in case of eucalyptus + wheat/rice
agroforestry system, grain yield of crops (rice and wheat) was reduced which was partially
compensated with value addition of eucalyptus wood. Srivastava and Ramamohanrao (1989)
also found that in alley cropping systems comprising of Lucaena lucocephala and sorghum,
monetary returns were higher as compared to sole cropping of sorghum.
Ahmed (1991) worked out detailed costs of agroforestry system for alkali soils and
analyzed mean annual production of Prosopis juliflora on soils having diverse pH status. He
concluded that in spite of high cost of establishing a plantation, an economic analysis of the
system yields 9.5% internal rate of return (IRR) which seems rationally high for degraded
lands and feasible within economic structure of this region. Various other alley cropping
cropping systems like Casurina intercropped with sorghum, pigeonpea and castor; teak
intercropped with turmeric) were found more profitable than sole tree farming systems
(Reddy et al., 1992; Sekar et al., 1993).
36
Bheemaiah et al. (1995) reported that intercropping of Faidherbia albida with
sunflower, castor and pigeonpea crops resulted in higher yield of intercrops and monetary
benefits as compared to their sole cropping. Similarly, Shrama (1996) found that economic
returns from Prosopis cineraria intercropped with pearl millet or mungbean were higher as
compared to sole cropping.
Dube et al. (2002) analyzed economical aspects of Eucalypt-based agroforestry
systems established in Brazil. The plantation of trees was made at a spacing of 10 × 4 m, and
different crops and pasture grasses were grown in association of woody pernnials in alley
farming design. The results showed that total cost on establishment and maintenance was
about 37% of total expenditure associated with these systems. Regarding revenue generated
out of these systems, about 50% of the revenues were received from the sale of wood
products following a rotation of 11-year. Variations in sale price of cattle affected sensitivity
analysis of the system to a considerable extent. Similarly variations in establishment cost and
intrest rate, also affected economic indicators of the whole system. Thus, it was concluded
that agroforestry systems were more economically sound as compared to monoculture
production systems.
Islam et al. (2008) conducted field experiments to evaluate growth performance of
winter vegetables under different multistrata systems viz., open field (100% PAR), coconut
and lemon based agroforesrtry system in Bangladesh. Results showed that significant
variations were observed regarding plant height of winter vegetables (except under
shade condition). On the other hand, significantly highest yield per plot and yield per hectare
were observed when plant grown under full sunlight condition. Economic analysis
showed that among the seven vegetables carrot gave the highest economic return
under multristrata coconut based agroforestry system. It was, therefore, concluded that
production of winter vegetables especially carrot and chilli under multistrata agroforestry
systems was economically profitable than sole production systems.
37
Chapter 3
MATERIALS AND METHODS
The research work was conducted to assess biomass productivity potential of
component species of biosaline agroforestry systems as affected by diverse intensity of soil
amendments added to soil in 2-year duration field experimentation (2011-13). Data regarding
growth behaviour of component species were recorded according to prescribed
methodologies and protocols.
3.1 Study area, site and climate
The studies were conducted at Bio-saline Research Station (BSRS), Pakka Anna,
Nuclear Institute for Agriculture and Biology (NIAB), Faisalabad, Pakistan (Longitude
73°.05´E and latitude 31°.24´N) with an elevation of 190 m asl. The climate of the area is
sub-tropical, semi-arid. The average temperature in the area is 32°C with average rainfall of
266 mm; evaporation exceeds 1600 mm. Detailed meterological data are given in table 3.1.
3.2 Soil and irrigation water characteristics
The soil at the station is saline sodic to sodic with medium to light texture in nature
whereas; underlain ground water is brackish and unfit for irrigation. Detailed analysis is
given in tables 3.2 and 3.3.
38
Table 3.1 Meterological data of site during the period April, 2011 to June, 2013.
Year M
on
th
Min
imu
m
Tem
pera
ture
(oC
)
Ma
xim
um
Tem
pera
ture
(oC
)
Av
era
ge
Tem
pera
ture
(oC
)
Rela
tiv
e
Hu
mid
ity
(%)
Ra
infa
ll
(mm
)
Net
Su
nsh
ine
(Ho
urs)
2011
Apr 19.4 34.3 26.9 41.7 16.8 9.27
May 24.7 40.4 32.6 31.4 10.3 10.36
Jun 27.2 40.8 34.0 33.6 68.7 9.37
Jul 27.6 38.2 32.9 59 151.4 9.13
Aug 27.5 36.8 32.2 65.8 89.9 8.47
Sep 23.5 34.7 29.1 59.3 165.3 8.25
Oct 20.7 33.6 27.2 57.6 0 8.21
Nov 12.5 28.8 20.7 58.9 0 8.41
Dec 9.4 21.7 15.6 68.9 0 6.39
2012
Jan 7.5 19.8 13.7 68 0 6.14
Feb 9.8 23.4 16.6 64.1 6 7.42
Mar 14.1 27.3 20.7 53.5 1.5 7.85
Apr 19.1 33.5 26.3 41.7 10.5 9.35
May 24.8 40.1 32.5 31.4 0 10.47
Jun 27 41.7 34.4 33.6 5.6 9.33
July 27.9 38.8 33.4 59 98.0 9.17
Aug 27.6 37.6 32.6 65.8 18.0 8.42
Sep 23.7 35.4 29.6 59.3 139.7 8.26
Oct 20.2 33.8 27.0 57.6 33.3 8.13
Nov 12.2 28.3 20.3 58.9 0.0 8.44
Dec 9.4 22.9 16.2 68.9 9.0 6.27
2013
Jan 7.8 19.3 13.6 68 3.1 6.13
Feb 9.9 23.1 16.5 64.1 59.5 7.31
Mar 14.4 26.5 20.5 53.5 5.0 7.81
Apr 19.5 32.1 25.8 41.7 12.9 9.29
May 24.7 39.8 32.3 31.4 7.1 10.43
Jun 27.6 41.7 34.7 33.6 98.0 9.35
39
Table 3.2 Analysis of soil at the experimental site
Characteristics Unit Values
Study 1
(Wheat)
Study 2
(Para grass)
pH - 8.47-8.64 8.53-8.66
EC dS m-1 10.2-23.4 13.1-19.2
SAR Mmolc L-1 44.5-67.5 54.3-72.8
Texture - Sandy loam Sandy loam
Saturation percentage % 32.3 34.1
Bulk density Mg m–3 1.41 1.45
Total N g Kg– 1 0.49 0.43
Available P mg Kg–1 9.13 8.36
Available K mg kg–1 118 104
Organic matter g kg– 1 4.11 3.89
Gypsum Requirement (GR) Mg ha-1 13.7 17.3
Table 3.3 Analysis of irrigation water at the experimental site
Characteristics Unit Values
pH - 8.6
EC dS m-1 6.21
RSC Mmolc L-1 21.3
SAR Mmolc L-1 40.2
TSS Mg L-1 4347
Table 3.4: Physico-chemical characteristics of farm yard manure used in the experiments
Characteristics Unit Values
Total nitrogen (N) kg Mg-1 11.34
Mineral nitrogen (N) kg Mg-1 1.22
Organic carbon (C) kg Mg-1 163.00
pH - 7.84
40
3.3 Components of agroforestry systems
Tree based-alley cropping systems comprised of:
a. Perennial woody tree components
i. Acacia nilotica
ii. Eucalyptus camaldulensis
Pre-established plantations of both the above said tree species were utilized for
experimentation. The plantations had following fearures.
i. Age: 10 years
ii. Plantation density: 800 trees ha-1
iii. Planting geometery: Spacing; Row to row 5 m; Tree to tree 2.5 m.
b. Understorey annual crop/grass components (grown in alleys)
i. Wheat c.v. Sehar-2006
ii. Para grass (Brachiaria mutica)
The main plots (open field, Acacia nilotica and Eucalyptus camaldulensis) were
divided into sub plots and applied with different soil amendments.
3.4 Treatments, experimental design and field layout
The understorey agroforestry components (Wheat, para grass) were grown in open
field and intercropped with trees in inter-row spaces (alley). The treatments included are
mentioned in treatment plan. Inorganic source of nitrogen was commercial urea fertilizer (N
46%).
Treatment Plan
Treatments Agrisilviculture system Silvopastoral system
Wheat Para Grass
T0 Control (No amendment) Control (No amendment)
T1 Nitrogen 60 kg ha-1 Gypsum @ gypsum
requirement (GR) 100%
T2 Nitrogen 120 kg ha-1 Farmyard manure 20 Mg ha-1
T3 Farmyard manure 20 Mg ha-1 Gypsum @GR 50% +
Farmyard manure 10 Mg ha-1
T4 Nitrogen 60 kg + Farmyard
manure 20 Mg ha-1
Gypsum @GR 100% +
Farmyard manure 10 Mg ha-1
41
Figure 1. Agrisilviculture system
Sole cropping Sole plantation
Agroforestry
42
Figure 2. Silvopastoral system
Sole plantation Sole cropping
Agroforestry
43
General agronomic recommendations/practices regarding land preparation, seed rate, sowing
time, method, irrigation requirements and protection measures were followed.
Following factors formed the basis of trial (agri-silviculture system)
Study 1
i. Factor-1 2 alley positions regarding light (open field, under canopy)
ii. Factor-2 3 levels of nitrogen fertilizer (0, 60, 120 kg N ha-1).
iii. Factor-3 3 levels of farm yard manure (0, 10, 20 Mg ha-1).
Study 2
In case of agri-silvipastoral system, following factors formed the basis of trial.
i. Factor-1 2 alley positions regarding light (open field, under canopy)
ii. Factor-2 3 levels of gypsum (0, 50, 100% GR).
iii. Factor-3 3 levels of farm yard manure (0, 10, 20 Mg ha-1).
Field Area dimensions
For each system either agrisilviculture or silvopastoral (open and alley cropping design
(Acacia nilotica, Eucalyptus camaldulensis intercropped with wheat, para grass), following
were field area dimensions.
i. Sub plots 5
ii. Replications 4
iii. Total no. of plots=n 5x4 =20
iv. Experimental Design 3-Factor factorial RCB design
3.5 Tree and crop management
The above described treatments were replicated four times in a randomized complete
block design. The gross plot size for open, Acacia nilotica and Eucalyptus camaldulensis
plantation was 2500 m2 (in each trial case) whereas area of sub plot was 100 m2 (10×10 m);
thus we had a population of 08 trees in count. About 50 cm wide risers on all sides of each
sub plot and 1 m wide buffer strip was made for effective separation among treatment plots
within a block. Each sub plot thus received a particular treatment as per experimental plan
44
cited above. In order to avoid any possible interaction among sub plots, all sampling
procedure was restricted in the middle of each sub plot for biomass and yield estimation of
crops/grasses.
3.6 Light intensity
Light intensity was recorded weekly at 1200 h by Lux meter (Lutron Lx-101 Model:
LI-COR WALZ, Made in USA) in open field and each alley cropping system during the
whole course of experimentation as cited by Pandey et al. (2011).
3.7 Biomass estimation of understorey components
a. Wheat crop
Wheat crop grown in open field and in alley designs was harvested from experimental
plots on attaining maturity stage by using quadrat (size: 1.0 m2), threshed manually to
separate grains and straw to record data regarding yield and yield components (planting
density, plant height, number of tillers m-2, 1000-grains weight, biological yield ha-1 and
harvest index. Harvest Index was calculated using the formula;
Harvest index =Economic yield (grain)
Biological yield× 100
b. Para grass
Biomass of the grass in the interior of quadrat (size: 1.0 m2) was harvested to 5 cm
above the soil surface using sharp sickles from each experimental plot. Data were recorded
for stolon height (length), number of tillers m-2, fresh and dry weight ha-1. Dry
matter/biomass of samples was determined from a 500 g sample drawn from the
experimental plot(s) and dried in oven at 70 °C till attaining constant weight.
3.8 Tree growth estimation
Height and diameter at breast height (dbh) of trees included in all alley cropping
systems were measured to estimate tree volume periodically so as to determine mean annual
increment (MAI) in tree biomass volume as affected by application of amendments in
experimental alley cropping systems. Wood weight was calculated as per density of each
woody species i.e., Acacia nilotica and Eucalyptus camaldulensis woody density 809 and
45
681 kg per m3, respectively, in agro-climatic conditions of Faisalabad, Pakistan (Awan et al.,
2012).
3.9 Soil characteristics monitoring
Soil samples were collected periodically from each subplot (open field and tree
alleys) by making holes with the help of auger. The samples were air dried under
shade, ground, passed through a 2 mm sieve and stored. Analyses for various soil
characteristics including pH, electrical conductivity (EC) and sodium adsorption ratio (SAR)
were made following analytical procedures detailed below with the objective to monitor
changes in salinity status in soil profile with adoption of different land use systems (open
field and alley cropping) and application of different soil amendments applied to the field as
per experimental plan.
3.9.1 Analytical procedures
The analytical methods described by U.S. Salinity Laboratory Staff (1954) were
followed. Brief detail of protocols and procedures adopted is as under:
a. Soil texture
Hydrometer method (Bouyoucos, 1962) was followed for the analysis. Sodium
hexametaphosphate (NaPO3)6 was used as dispersing agent. Soil (50 g) was transferred into
mixing cup and distilled water was added. After it, 25 ml of 5% (NaPO3)6 solution was
added and after shaking the sample mechanically for 15 minutes, the suspension was
transferred into 1 L graduated cylinder to make the volume 1 L including hydrometer
displacement. Hydrometer was inserted in the cylinder after vigorous shaking and readings
were noted after 40 seconds and 2 hours for silt+clay and clay, respectively. Textural class
was designated following the International Textural Triangle.
b. Soil saturated paste
A known weight of soil (400 g) was soaked with distilled water and allowed to stand
overnight. Then the saturated paste was made which glistened, did not accumulate water in
depression and fell freely from spatula.
46
Saturation percentage
A known weight of saturated paste was oven dried at 105 oC and saturation
percentage of soil was determined by the formula:
SP =Loss in weight on oven drying (g)
Oven dried wt.of soil (g)× 100
c. Bulk density
Bulk density was measured using a core inserted to a depth of 5 cm. The bulk density
was measured on surface layer and on the soil immediately below the layer (i.e., 5 -10 cm).
The soil extending beyond each end of the core was trimmed with a sharp spatula. The soil
sample volume was thus established to be the same as the inner volume of the core. The soil
material from the core was transferred to a contained. All the samples obtained were dried in
an oven at 105 oC to a constant weight. Oven dry weight of all the samples was measured and
the bulk density was calculated (Blake and Hartage, 1986) by using the formula.
Bulk density (gcm−3) =Oven dry mass of the sample (g)
Volume of sample (cm3)
d. Soil pH
Soil pH was recoded using pH meter after standardizing it with buffer solutions of
7.01 and 9.02 pH (Method 21a).
e. Soil Electrical Conductivity
Electrical conductivity (EC) in soil extract and in water samples was determined by
electrical conductivity meter (HANNA HI-8033) after standardizing it with 0.01 N KCl
solution.
Cell constant (k) was calculated by the formula:
K =1.4118dSm−1
EC of 0.01NKCl (dSm−1)
47
The ECe was converted into TSS (mmolc L-1) with the help of graph (average line) at
page 12 of USDA Handbook No. 60 (US Salinity Laboratory Staff, 1954).
f. Cations determination (Na+, K+)
Flame photometer (Jenway PEP-7) was used to determine potassium (K+) and sodium
(Na+) cations in diluted extracts by using potassium and sodium filter. The instrument was
standardized with a series of Na+ and K+ solutions of varying concentrations of either cation.
g. Soluble Ca2++ Mg2+ cations
These cations were determined by titrating the saturation extract against 0.01 N
EDTA (disodium) solution to a blue end point using Eriochrome Black T (EBT) indicator in
the presence of NH4OH +NH4Cl buffer solution.
h. Sodium adsorption ratio (SAR)
Sodium (Na+) was determined by flame photometer and Ca2+ + Mg2+ concentrations
were determined by titration method. The SAR in soil extract or water sample was calculated
using the following expression.
SAR =Na+
√[(Ca2++Mg2+)/2] (MmolcL−1)
i. Residual Sodium Carbonate (RSC)
Samples of irrigation water were collected in plastic bottles at source. The analytical
methods described by U.S. Salinity Lab. Staff were used. Water residual sodium carbonate
(RSC) was determined with the help of formula (Eaton, 1950) as:
RSC= (CO32- +HCO3
1-) - (Ca2+ +Mg2+), all expressed as mmolc L-1.
j. Gypsum requirement (GR)
In the estimation of gypsum requirement of saline-sodic/sodic soils, the attempt is to
measure the quantity of gypsum (Calcium sulphate) required to replace the sodium from
the exchange complex. The sodium so replaced with calcium of gypsum is removed
through leaching of the soil. The soils treated with gypsum become dominated with
48
calcium in the exchange complex. When Calcium of the gypsum is exchanged with
sodium, there is reduction in the calcium concentration in the solution. The quantity of
calcium reduced is equivalent to the calcium exchanged with sodium. It is equivalent to
gypsum requirement of the soil when ‘Ca’ is expressed as CaSO4. Soil was shaken
mechanically with saturated gypsum solution (Ca2+ concentration=28 Mmolc L-1 for 30
minutes (Schoonover, 1952). Suspension was filtered. The filterate was analyzed for Ca2+
+Mg2+ by titrating against 0.01N EDTA solution using NH4Cl+NH4OH buffer solution
and erichrome black T as an indicator, to blue end point. Gypsum requirement (GR) was
calculated from the difference of Ca2+ +Mg2+ concentration of gypsum saturated solution
and filterate (mmolc L-1).
GR (cmolcKg−1) = [Ca2+ + Mg2+ in soil soln. ] − [Ca2+ + Mg2+ in gyp. soln. ]
1000×
100
wt. of soil (g)× 100
k. Soil nitrogen
Soil total N for each experimental plot was determined calorimetrically, following the
Kjeldahl procedure (Bremmer and Mulvaney, 1982). In this method, 0.2g of sampled
soil was digested with 3 ml of concentrated H2SO4 in the presence of digestion mixture
containing K2SO4, CuSO4 and Se on block digest for about 4-5 hours. The digestion was
initially started at 50 ºC and then the temperature was raised gradually to 100, 150. 200, 250,
300 and finally to 350 ºC, which was maintained at least for 1 hour to turn the
sample color to light greenish or colorless. After cooling, the digest was transferred to a
100 ml volumetric flask and the volume makes up with distilled water. 20 ml of the
digest was distilled in the presence of 5ml of 40% NaOH solution and 5 ml boric acid mixed
indicator. The distillate was titrated against standard 0.005M HCl and N was calculated as 1
ml of 0.005M HCl is equivalent to 70 µg. A blank reading was also taken at the same time.
49
3.10 Statistical analysis
Statistical analysis for the measured growth data regarding biomass productivity of
both the components (trees and understorey components) of alley cropping systems for all
the treatments was carried out by computing ANOVA in Randomized Complete Block
Design using Statistix ver. 8.1. The significance of the mean differences between species and
amendments was tested using an analysis of variance based on a two factor factorial design.
In case of significant differences, least significant difference (LSD) test, and standard
error of means (Gomez and Gomez, 1984) were used to separate the means. Fisher’s LSD
test was applied with a probability level (P≤0.05) to compare the mean differences (Steel et
al., 1997) whereas graphs were plotted in EXCEL package.
50
Chapter 4
RESULTS AND DISCUSSION
The studies were designed to assess the effect of various soil amendments on growth of
various tree species and intercropped understorey crop/grass employing standard techniques
and protocols as described in Chapter 3. Detailed account of results obtained in these studies
is discussed as under.
4.1 Study 1: Interactive effect of varying levels of nitrogen and farm manure on
biomass production of wheat in open field, Acacia- and Eucalyptus based alley cropping
systems with different light intensity regimes
4.1.1 Wheat growth and production
4.1.1.1 Plant density
The results of plant density of wheat crop (plants m-2) are presented in Table 4.1,
which showed significant interactive effect of varying levels of nitrogen and farm manure on
plant density (m-2) of wheat in open field, Acacia and Eucalyptus-based alley cropping
systems with different light intensity regimes. These results indicate that average number of
plants produced in each treatment of experimental plot increased significantly with increase
in fertility status in all the systems (open and agroforestry systems).
In open field conditions, the lowest plant density was 97 plants m-2 in control plots
(no amendment) whereas its highest count was 172 plants m-2 (77.3% higher) in plots applied
with (N 60 kg + FYM 20 Mg ha-1) in 1st year of experimentation (2011-12). During 2nd year
(2012-13), the lowest plant density was 102 in control plots whereas, its highest value was
184 plants m-2 (80.4% higher) in plots having treatment (N 60 kg + FYM 20 Mg ha-1).
Combined data for both the years showed that plant density increased from 100 (control) to
177 plants m-2 (77% higher) in fertilized treatment (N 60 kg + FYM 20 Mg ha-1).
51
In Acacia-based agroforestry system, the lowest plant density was 86 plant m-2 in
control plots (no amendment), whereas its highest value was 156 plants m-2 (81.4% higher) in
plots applied with treatment (N 60 kg + FYM 20 Mg ha-1) in 1st year of experimentation
(2011-12). In 2nd year (2012-13), plant density was 92 plants m-2 in control plots (no
amendment) whereas it was 160 plants m-2 (73.9% higher) in plots receiving (N 60 kg +
FYM 20 Mg ha-1). Mean of both the years showed that plant density was 89 plants m-2
(control) whereas it was 158 plants m-2 (77.5% higher) in fertilized treatment (N 120 kg ha-1).
In Eucalyptus-based agroforestry system, the lowest plant density was 75 plant m-2 in
control plots (no amendment) whereas its highest value was 137 plants m-2 (82.7%) in plots
applied with treatment (N 60 kg + FYM 20 Mg ha-1) during 1st year of experimentation
(2011-12). In 2nd year (2012-13), plant density was 80 plants m-2 in control plots (no
amendment) whereas it was 135 plants m-2 (68.8% higher) in plots applied with treatment (N
60 kg + FYM 20 Mg ha-1). Mean of both the years showed that plant density was 77 plants
m-2 in control plots whereas it was 136 plants m-2 (76.6% higher) in fertilized treatment (N
60 kg + FYM 20 Mg ha-1).
Over all comparison of light factor in open field, Acacia-based and Eucalyptus-based
systems showed that plant density was significantly affected in all the systems. Plant density
exhibited decreasing trend from 149 plants m-2 (open field) to 133 (10.7% lower) (Acacia-
based) and 116 plants m-2 (22.1% lower) in Eucalyptus-based agroforestry system.
Comparison of soil fertility in all the systems under study i.e., open field, Acacia-
based and Eucalyptus-based systems, revealed that plant density increased with the
application of soil amendments in all the systems. A significant increase in plant density was
recorded from 89 (no amendment) to 157 plants m-2 (N 60 kg + FYM 20 Mg ha-1).
52
Table 4.1 Effect of fertilizer application on plant density (plants m-2) of wheat grown in open field, Acacia-based and
Eucalyptus-based agroforestry systems
Treatments Open field
(PAR 100%)
Acacia-based agroforestry
system (PAR 73±3%)
Eucalyptus-based agroforestry
system (PAR 64±3%)
Grand
Mean
Year-1 Year-II Mean Year-I Year-II Mean Year-I Year-II Mean
Control
(T0) 97±5.04 102.0±5.67 100d 86±2.88 92±5.18 89.4d 75±4.71 80±4.05 77.5d 89 d
N 60 Kg ha-1
(T1) 137±7.03 145±5.81 141c 124±4.85 126±5.52 126c 109±4.92 112±3.44 111c 126c
N 120 Kg ha-1
(T2) 170±6.59 179±9.15 175a 154±10.9 151±9.67 152a 136±13.72 134±3.92 135a 155a
FYM 20 Mg ha-1
(T3) 147±6.05 154±6.36 151b 136±7.26 139±8.69 137b 115±17.02 118±5.25 117b 135b
N 60 Kg + FYM 20
Mg ha-1 (T4) 172±5.96 184±7.24 177a 156±7.74 160±9.46 158a 137±11.39 135±4.99 136a 157a
Mean 144.8 153.02
131.5 133.6
114.56 116.40
149A 133B 116C
Means values followed by different letter(s) in each category are statistically different using least significantly difference (LSD) test at 5% level of probability.
53
4.1.1.2 Plant height
The results of plant height of wheat crop (Table 4.2) showed significant interactive
effect of varying levels of nitrogen and farm manure on plant height (cm) of wheat in open
field, Acacia-based and Eucalyptus based-alley cropping systems with different regimes of
light intensity. These results indicated that plant height in each treatment of experimental plot
increased with increase in fertility status in all the systems (open and agroforestry systems).
In open field conditions, plant height was 91.6 cm in control plots (no amendment)
whereas it was 98.6 cm in plots (7.6% higher) applied with (N 60 kg + FYM 20 Mg ha-1) in
1st year of experimentation (2011-12). During 2nd year (2012-13), plant height was 93.4 cm
in control plots whereas it was 101 cm (8.1% higher) in plots having treatment (N 60 kg +
FYM 20 Mg ha-1). Combined data for both the years showed that plant height increased from
92.5 (control) to 99.7 cm (7.8% higher) (N 60 kg + FYM 20 Mg ha-1).
In Acacia-based alley cropping system, plant height was 81.8 cm in treatment plots
(no amendment) whereas it was 99.3 cm (21.4% higher) in treatment plots receiving (N 60
kg + FYM 20 Mg ha-1) during 1st year of experimentation (2011-12). In 2nd year (2012-13),
plant height was 82.7 cm in control plots (no amendment) whereas it was 99.7 cm (20.6%
higher) in plots receiving treatment (N 60 kg + FYM 20 Mg ha-1). Mean of both the years
showed that plant height was 99.5 cm in plots having treatment (N 60 kg + FYM 20 Mg ha-1)
as compared to 82.2 cm of control (21% higher) .
In Eucalyptus-based agroforestry system, plant height was 78.8 cm in treatment plots
(no amendment) whereas it was 92.2 cm (17% higher) in treatment plots receiving (N 60 kg
+ FYM 20 Mg ha-1) 1st year of experimentation (2011-12). In 2nd year (2012-13), plant
height was 79.7 cm in control plots (no amendment) whereas it was 93.4 cm (17.2% higher)
in plots receiving treatment (N 60 kg + FYM 20 Mg ha-1). Mean of both the years showed
that plant height was 92.8 cm in fertilized treatment (N 60 kg + FYM 20 Mg ha-1) as
compared to 79.2 cm in control (17.2% higher) .
54
Over all comparison of light factor in open field, Acacia-based and Eucalyptus-based
systems showed that plant height was significantly affected in all the systems. Plant height
exhibited decreasing trend from 96.2 cm (open field) to 92 cm (4.4% lower) in Acacia and
86.4 cm (10.2% lower) Eucalyptus-based agroforestry system.
Comparison of soil fertility in all three systems under study i.e., open field, Acacia
and Eucalyptus-based systems, revealed that plant height increased gradually with the
application of soil amendments in all the systems. A progressive increase in plant height was
recorded from 86.4 cm (no amendment) to 97.3 cm (12.6% higher) (N 60 kg + FYM 20 Mg
ha-1).
55
Table 4.2 Effect of fertilizer application on plant height (cm) of wheat grown in open field, Acacia-based and Eucalyptus-based
agroforestry systems.
Treatments Open field
(PAR 100%)
Acacia-based agroforestry
system (PAR 73±3%)
Eucalyptus-based agroforestry
system (PAR 64±3%)
Grand
Mean
Year-1 Year-II Mean Year-I Year-II Mean Year-I Year-II Mean
Control
(T0) 91.6±0.86 93.4±0.65 92.5e 81.8±0.81 82.7±1.57 82.2e 78.8±1.46 79.7±0.83 79.2e 84.6 e
N 60 Kg ha-1
(T1) 93.5±0.51 94.9±0.75 94.2d 85.3±0.41 87.1±1.02 86.2d 82.2±1.24 84.4±0.84 83.3d 87.9 d
N 120 Kg ha-1
(T2) 95.8±0.87 97.6±0.94 96.7c 94.7±2.67 96.3±1.63 95.5c 86.8±1.31 90.4±1.09 89.5b 93.9 c
FYM 20 Mg ha-1
(T3) 97.1±0.84 98.5±0.77 97.8b 96.5±0.84 96.9±1.37 96.7b 88.9±1.25 87.3±0.89 88.2c 94.2b
N 60 Kg + FYM
20 Mg ha-1 (T4) 98.6±1.06 100.8±0.79 99.7a 81.8±0.81 82.7±1.57 82.2e 92.2±1.15 93.4±2.85 92.8a 97.3 a
Mean
95.3 97.04 96.2 91.52 92.54 92.0 85.78 87.04 84.6
96.2A 92.00B 86.4C
Means values followed by different letter(s) in each category are statistically different using least significantly difference (LSD) test at 5% level of probability.
56
4.1.1.3 Leaf area
The results of leaf area of wheat (Table 4.3) showed significant interactive effect of
varying levels of nitrogen and farm manure on leaf area (cm2) of wheat in open field, Acacia-
based and Eucalyptus-based alley cropping systems with different light intensity regimes.
These results indicated that plant leaf area in each treatment of experimental plot increased
with increase in fertility status in all the systems (open and agroforestry systems).
In open field conditions, leaf area was 21.1 cm2 in control plots (no amendment)
whereas it was 25.6 cm2 (21.3% higher) in plots applied with fertilized treatment (N 60 kg +
FYM 20 Mg ha-1) in 1st year of experimentation (2011-12). During 2nd year (2012-13), leaf
area was 22.1 cm2 in control plots whereas it was 27.4 cm (24% higher) in plots having
fertilized treatment (N 60 kg + FYM 20 Mg ha-1). Combined data for both the years showed
that leaf area increased from 21.6 (control) to 26.6 cm2 (23.1% higher) (N 60 kg + FYM 20
Mg ha-1).
In Acacia-based agroforestry system, leaf area was 19.7 cm2 in control plots (no
amendment) whereas it was 24.6 cm2 (24.9% higher) in plots fertilized with (N 60 kg + FYM
20 Mg ha-1) during 1st year of experimentation (2011-12). In 2nd year (2012-13), leaf area
was 21.1 cm2 in control plots (no amendment) whereas it was 26.08 cm2 (23.6% higher) in
plots where the treatment (N 60 kg + FYM 20 Mg ha-1) was applied. Mean of both the years
showed that leaf area was higher in highly fertilized plots, as it was 20.4 cm2 in control
while it was 25.3 cm2 (24% higher) in plots applied with treatment (N 60 kg + FYM 20 Mg
ha-1).
In Eucalyptus-based agroforestry system, leaf area was 18.1 cm2 in control plots (no
amendment) whereas it was 22.9 cm2 (26.5% higher) in treatment plots (N 60 kg + FYM 20
Mg ha-1) in 1st year of experimentation (2011-12). In 2nd year (2012-13), leaf area was 19
cm2 in control plots (no amendment) whereas it was 23.8 cm2 (25.3% higher) in plots
receiving treatment (N 60 kg + FYM 20 Mg ha-1). Mean of both the years showed that leaf
area was 23.4 cm2 in treatment where treatment (N 60 kg + FYM 20 Mg ha-1) was used as
compared to 18.6 cm2 (25.8% higher) in control plot (no amendment).
57
Comparison of light factor in all the systems under observation (open field, Acacia-
based and Eucalyptus-based systems), showed that leaf area was significantly affected in all
the systems. Leaf area showed decreasing trend from 24.4 cm2 (open field) to 23.3 cm2 (4.1%
lower) in Acacia-based and 21.3 cm2 (12.7% low) in Eucalyptus-based agroforestry system.
Comparison of soil fertility in all three systems under study i.e., open field, Acacia-
based and Eucalyptus-based systems, revealed that leaf area gradually increased with the
application of soil amendments in all the systems. A progressive increase in leaf area was
recorded from 20.2 cm2 (no amendment) to 25.1 cm2 (24.3% higher) in fertilized treatment
(N 60 kg + FYM 20 Mg ha-1).
58
Table 4.3 Effect of fertilizer application on plant leaf area (cm2) of wheat grown in open field, Acacia-based and Eucalyptus-
based agroforestry systems.
Treatments Open field
(PAR 100%)
Acacia-based agroforestry
system (PAR 73±3%)
Eucalyptus-based
agroforestry system (PAR
64±3%)
Grand
Mean
Year-1 Year-II Mean Year-I Year-II Mean Year-I Year-II Mean
Control
(T0) 21.1±0.61 22.1±0.51 21.6d 19.7±0.63 21.1±0.54 20.4c 18.1±0.74 19.0±0.39 18.6d 20.2d
N 60 Kg ha-1
(T1) 23.3±0.44 23.1±0.49 23.5c 22.3±0.41 22.1±0.17 22.2b 20.6±0.49 20.7±0.42 20.7c 22.3c
N 120 Kg ha-1
(T2) 25.1±0.42 25.4±0.38 25.3b 23.8±0.37 24.3±1.06 24.1ab 21.7±0.86 22.1±0.18 21.9b 23.7b
FYM 20 Mg ha-1
(T3) 24.2±0.43 25.6±0.48 24.9b 23.1±0.18 24.4±1.09 23.8b 21.2±0.22 22.7±0.31 21.9b 23.6b
N 60 Kg + FYM
20 Mg ha-1 (T4) 25.6±0.45 27.3±0.35 26.6a 24.5±1.39 26.1±0.44 25.3a 22.9±0.23 23.8±1.20 23.4a 25.1a
Mean
23.7 24.8 22.7 23.6 20.9 21.68
24.4A 23.3B 21.3C
Means values followed by different letter(s) in each category are statistically different using least significantly difference (LSD) test at 5% level of
probability.
59
4.1.1.4 Number of tillers m-2
The results of number of tillers m-2 (Table 4.4) showed significant interactive effect of
varying levels of nitrogen and farm manure on number of tillers m-2 of wheat in open field,
Acacia-based and Eucalyptus-based alley cropping systems with different light intensity
regimes. These results indicated that number of tillers m-2 in each treatment of experimental
plot increased with increase in fertility status in all the systems (open and agroforestry
systems).
In open field conditions, number of tillers was 295 m-2 in control plots (no
amendment) whereas it was 413 m-2 (40% higher) in plots applied with treatment (N 60 kg +
FYM 20 Mg ha-1) in 1st year of experimentation (2011-12). During 2nd year (2012-13),
number of tillers was 307 m-2 in control treatment plots whereas it was 436 (42% higher) in
plots having treatment (N 60 kg + FYM 20 Mg ha-1). Combined data for both the years
showed that number of tillers increased from 301 (control) to 424 m-2 (40.9% higher) (N 60
kg + FYM 20 Mg ha-1).
In Acacia-based agroforestry system, number of tillers m-2 was 217 in control plots
(no amendment) whereas it was 356 m-2 (64.1% higher) in treatment plots receiving
treatment (N 60 kg + FYM 20 Mg ha-1) in 1st year of experimentation (2011-12). In 2nd year
(2012-13), number of tillers m-2 was 236 in control plots (no amendment) whereas it was
398 (68.6% higher) in plots receiving treatment (N 60 kg + FYM 20 Mg ha-1). Mean of both
the years showed that number of tillers m-2 was 377 m-2 in plots having treatment (N 60 kg +
FYM 20 Mg ha-1) as compared 226 m-2 in control plots (66.8% higher).
In Eucalyptus-based agroforestry system, number of tillers was 195 m-2 in control
plots (no amendment) whereas it was 336 m-2 (72.3% higher) in treatment plots receiving (N
60 kg + FYM 20 Mg ha-1) in 1st year of experimentation (2011-12). In 2nd year (2012-13),
number of tillers m-2 was 207 in control plots (no amendment) whereas they were 347 in
plots (67.6% higher) receiving (N 60 kg + FYM 20 Mg ha-1). Mean of both the years showed
that number of tillers was 341 m-2 (69.7% higher) in fertilized plots (N 60 kg + FYM 20 Mg
ha-1) as compared to control plots where number of tillers was 201 m-2.
60
Comparison of light factor in all the systems under observation (open field, Acacia-
based and Eucalyptus-based systems), showed that number of tillers m-2 was significantly
affected in all the systems. Number of tillers m-2 exhibited decreasing trend from 367 m-2
(open field) to 323 m-2 (12% lower) in Acacia and 283 m-2 (22.9% lower) in Eucalyptus-
based agroforestry system.
Comparison of soil fertility in all three systems under study i.e., open field, Acacia
and Eucalyptus-based systems, revealed that number of tillers m-2 gradually increased with
application of soil amendments in all the systems. A progressive increase in number of tillers
m-2 was recorded from 243 m-2 (no amendment) to 381 m-2 (56.8% higher) (N 60 kg + FYM
20 Mg ha-1).
61
Table 4.4 Effect of fertilizer application on on number of tiller (m-2) of wheat grown in open field, Acacia-based and
Eucalyptus-based agroforestry systems.
Treatments Open field
(PAR 100%)
Acacia-based agroforestry
system (PAR 73±3%)
Eucalyptus-based
agroforestry system (PAR
64±3%)
Grand
Mean
Year-1 Year-II Mean Year-I Year-II Mean Year-I Year-II Mean
Control
(T0) 295±7.61 307±6.94 301e 217±5.9 236±8.6 226c 195±8.41 207±8.49 201d 243e
N 60 Kg ha-1
(T1) 337±8.96 345±6.52 341d 297±14.8 334±10.7 315b 260±7.25 276±12.3 268c 308d
N 120 Kg ha-1
(T2) 387±9.21 402±9.39 394b 354±13.9 376±13.2 365a 300±10.2 319±10.2 309b 356b
FYM 20 Mg ha-1
(T3) 365±6.58 381±5.49 373c 319±11.8 347±12.6 333b 294±8.28 292±10.3 293b 333c
N 60 Kg + FYM
20 Mg ha-1 (T4) 413±6.91 436±8.79 424a 356±11.0 398±8.5 377a 336±9.28 347±11.3 341b 381a
Mean
359 374 308 338 277 288
367A 323B 283C
Means values followed by different letter(s) in each category are statistically different using least significantly difference (LSD) test at 5% level of probability.
62
4.1.1.5 Number of grains spike -1
The results of number of grains spike-1 (Table 4.5) showed significant interactive
effect of varying levels of nitrogen and farm manure on number of grains spike-1 of wheat in
open field, Acacia-based and Eucalyptus-based alley cropping systems with different light
intensity regimes. These results indicated that number of grains spike-1 in each treatment of
experimental plot increased with increase in fertility status in all the systems (open and
agroforestry systems).
In open field conditions, number of grains spike-1 was 44 in control plots (no
amendment) whereas it was 57 (29.5% higher) in plots applied with fertility treatment (N 60
kg + FYM 20 Mg ha-1) in 1st year of experimentation (2011-12). During 2nd year (2012-13),
number of grains spike-1 was 44 in control treatment plots whereas it was 59 (34.1% higher)
in plots having treatment (N 60 kg + FYM 20 Mg ha-1). Combined data for both the years
showed that number of grains spike-1 increased from 44 (control) to 58 (31.8% higher) in
treatment plots incorporated with treatment (N 60 kg + FYM 20 Mg ha-1).
In Acacia-based agroforestry system, number of grain spike-1 were 31 in control plots
(no amendment) whereas it was 43 (38.7% higher) in plots receiving fertility treatment (N 60
kg + FYM 20 Mg ha-1) in 1st year of experimentation (2011-12). In 2nd year (2012-13),
number of grains spike-1 was 32 in control plots (no amendment) whereas it was 42 (31.3%
higher) in plots applied with fertility treatment (N 60 kg + FYM 20 Mg ha-1). Mean of both
the years showed that number of grains spike-1 was improved as it was 31 in control plots
whereas it was 43 (38.7% higher) in plots having fertility treatment (N 60 kg + FYM 20 Mg
ha-1).
In Eucalyptus-based agroforestry system, number of grains spike-1 was 29 in control
plots (no amendment) whereas it was 40 (37.9% higher) in treatment plots rapplied with
treatment (N 60 kg + FYM 20 Mg ha-1) in 1st year of experimentation (2011-12). In 2nd year
(2012-13), number of grains spike-1 was 29 in control plots (no amendment) whereas it was
41 (41.4% higher) in plots receiving fertility treatment (N 60 kg + FYM 20 Mg ha-1). Mean
of both the years showed that number of grains spike-1 was 29 in control plots whereas it was
40 (37.9% higher) in plots applied with treatment (N 60 kg + FYM 20 Mg ha-1).
63
Comparison of light factor in all the systems under observation (open field, Acacia-
based and Eucalyptus-based systems), showed that number of grains spike-1 was significantly
affected in all the systems. Number of grains spike-1 exhibited decreasing trend from 50 (open
field) to 38 (24% lower) in Acacia-based and 35 (30% lower) in Eucalyptus-based
agroforestry system.
Comparison of soil fertility in all three systems under study i.e., open field, Acacia
and Eucalyptus-based systems, revealed that number of grains spike-1 gradually increased
with application of soil amendments in all the systems. A progressive increase in number of
grains spike-1 was recorded from 35 (no amendment) to 47 (34.3% higher) in plots applied
with treatment (N 60 Kg + FYM 20 Mg ha-1).
64
Table 4.5 Effect of fertilizer application on number of grains spike -1of wheat grown in open field, Acacia-based and
Eucalyptus-based agroforestry systems.
Treatments Open field
(PAR 100%)
Acacia-based agroforestry
system (PAR 73±3%)
Eucalyptus-based
agroforestry system (PAR
64±3%)
Grand
Mean
Year-1 Year-II Mean Year-I Year-II Mean Year-I Year-II Mean
Control
(T0) 44±0.32 44±0.38 44d 30±1.35 32±1.14 31d 28±0.53 30±0.59 29e 35d
N 60 Kg ha-1
(T1) 48 ±0.39 46±0.58 47cd 34±2.05 34±0.91 34c 31 ±0.89 33±0.87 32d 38c
N 120 Kg ha-1
(T2) 53±0.82 51±0.68 52b 40±1.79 40±1.09 40b 34±1.41 36±1.07 35c 41b
FYM 20 Mg ha-1
(T3) 48±0.32 50±0.27 49bc 39 ±1.21 41±1.52 40b 39±1.82 37±1.21 38b 43b
N 60 Kg + FYM
20 Mg ha-1 (T4) 57±0.23 59±0.33 58a 43±1.20 42±1.37 41a 40±1.04 42±1.02 41a 47a
Mean
49.5 50.5 38.06 37.82 34.4 35.4
50A 38B 35C
Means values followed by different letter(s) in each category are statistically different using least significantly difference (LSD) test at 5% level of probability.
65
4.1.1.6 1000-grains weight
The results of 1000-grains weight (Table 4.6) showed significant interactive effect of
varying levels of nitrogen and farm manure on 1000-grains weight of wheat in open field,
Acacia-based and Eucalyptus-based alley cropping systems with different light intensity
regimes. These results indicated that 1000-grains weight in each treatment of experimental
plot increased with the increase in fertility status in all the systems (open and agroforestry
systems).
In open field conditions, 1000-grains weight was 40.4 g in control plot (no
amendment) whereas it was 44.8 g (10.9% higher) in plots applied with fertility treatment (N
60 kg + FYM 20 Mg ha-1) in 1st year of experimentation (2011-12). During 2nd year (2012-
13), 1000-grains weight was 40.9 g in control plots whereas it was 45.7 g (11.7% higher) in
plots having treatment (N 60 kg + FYM 20 Mg ha-1). Combined data for both the years
showed that 1000-grains weight increased from 40.6 g (control) to 45.3 g (11.6% higher) in
fertility treatment (N 60 kg + FYM 20 Mg ha-1).
In Acacia-based agroforestry system, 1000-grains weight was 34.7 g in control plot
(no amendment) whereas it was 40.8 g (17.6% higher) in plots receiving fertility treatment
(N 60 kg + FYM 20 Mg ha-1) in 1st year of experimentation (2011-12). In 2nd year (2012-
13), 1000-grains weight was 35.7 g in control plots (no amendment) whereas it was 39.9 g
(11.8% higher) in plots receiving fertility treatment (N 60 kg + FYM 20 Mg ha-1). Mean of
both the years showed that 1000- grains weight was higher in fertilized treatments as it was
35.2 g (control) whereas it was 40.3 g (14.5% higher) in plots applied with fertility treatment
(N 60 kg + FYM 20 Mg ha-1).
In Eucalyptus-based agroforestry system, 1000-grains weight was 32.3 g in control
plots (no amendment) whereas it was 37.2 g (15.2% higher) in treatment plots receiving
treatment (N 60 kg + FYM 20 Mg ha-1) in 1st yeaper of experimentation (2011-12). In 2nd
year (2012-13), 1000-grains weight was 33.8 g in control plots (no amendment) while it was
38.4 g (13.6% higher) in plots receiving treatment (FYM 20 Mg + N 60 kg ha-1). Mean of
both the years showed that 1000-grains weight was higher in fertilized treatments was 37.8 g
66
in fertilized treatment (N 60 kg + FYM 20 Mg ha-1) whereas it was 33 g in control (12.1%
higher).
Comparison of light factor in all the systems under observation (open field, Acacia-
based and Eucalyptus-based systems), showed that 1000-grains weight was significantly
affected in all the systems. 1000-grains weight showed a decreasing trend from 43.4 g (open
field) to 37.8 g (12.9 % lower) in Acacia-based and 35 g (19.4% lower) in Eucalyptus-based
agroforestry system.
Comparison of soil fertility in all three systems under study i.e., open field, Acacia-
based and Eucalyptus-based systems, revealed that 1000-grains weight gradually increased
with application of soil amendments in all the systems. A progressive increase in 1000-grains
weight was recorded from 36.3 g (no amendment) to 41.1 g (3.2% higher) in plots applied
with fertility treatment (N 60 kg + FYM 20 Mg ha-1).
67
Table 4.6 Effect of fertilizer application on 1000-grains weight of wheat grown in open field, Acacia-based and Eucalyptus-
based agroforestry systems.
Treatments Open field
(PAR 100%)
Acacia-based agroforestry
system (PAR 73±3%)
Eucalyptus-based agroforestry
system (PAR 64±3%)
Grand
Mean
Year-1 Year-II Mean Year-I Year-II Mean Year-I Year-II Mean
Control
(T0) 40.4±0.46 40.9±0.39 40.6d 34.7±0.57 35.6±0.59 35.2d 32.2±0.88 33.8±0.78 33.0c 36.3e
N 60 Kg ha-1
(T1) 42.4±0.25 43.1±0.43 42.8c 36.5±0.90 37.0±0.51 36.8c 33.5±1.48 34.6±0.82 34.1bc 37.9d
N 120 Kg ha-1
(T2) 44.1±0.35 44.8±0.38 44.5b 38.3±0.53 39.6±0.64 39b 35.1±0.86 36.4±1.11 35.8b 39.7b
FYM 20 Mg ha-1
(T3) 43.4±0.22 44.5±0.35 43.9b 37.2±0.37 38.1±0.6 37.7c 33.7±0.77 34.9±1.02 34.3bc 38.6c
N 60 Kg + FYM
20 Mg ha-1 (T4) 44.8±0.43 45.7±0.20 45.3a 40.7±0.97 39.9±0.86 40.3a 37.2±1.61 38.4±0.67 37.8a 41.1a
Mean
43.1 43.8 37.5 38.1 34.4 35.6
43.4A 37.8B 35.03C
Means values followed by different letter(s) in each category are statistically different using least significantly difference (LSD) test at 5% level of probability.
68
4.1.1.7 Grain yield
The results of grain yield (Table 4.7) showed significant interactive effect of varying
levels of nitrogen and farm manure on grains yield of wheat in open field, Acacia-based and
Eucalyptus-based alley cropping systems with different light intensity regimes. These results
indicated that grain yield increased in each experimental plot with increase in fertility status
in all the systems (open and agroforestry systems).
In open field conditions, grain yield was 1611 kg ha-1 in control plots (control)
whereas it was 3087 kg ha-1 (91.6% higher) in plots applied with fertility treatment (N 60 kg
+ FYM 20 Mg ha-1) in 1st year of experimentation (2011-12). During 2nd year (2012-13),
grain yield was 1635 kg ha-1 in control plots whereas it was 3157 kg ha-1 (93.1% higher) in
plots having treatment (N 60 kg + FYM 20 Mg ha-1). Combined data for both the years
showed that grain yield increased from 1623 (control) to 3122 kg ha-1 (92.4% higher) (N 60
kg + FYM 20 Mg ha-1).
In Acacia-based agroforestry system, grain yield was 1337 kg ha-1 in control
treatment plots (no amendment; control) whereas it was 2428 kg ha-1 (81.6% higher) in plots
applied with treatment (N 60 kg + FYM 20 Mg ha-1) in 1st year of study (2011-12). During
2nd year (2012-13), grain yield was 1441 kg ha-1 in control plots whereas it was 2682 kg ha-1
(86.1% higher) in plots applied with treatment (N 60 kg + FYM 20 Mg ha-1). Combined data
for both the years showed that grain yield increased from 1389 (control) to 2555 kg ha -1
(83.9% higher) (N 60 kg + FYM 20 Mg ha-1).
In Eucalyptus-based agroforestry system, grain yield was 1149 kg ha-1 in control plots
(no amendment; control) whereas it was 2112 kg ha-1 (83.8% higher) in plots applied with
treatment (N 60 kg + FYM 20 Mg ha-1) in 1st year of experimentation (2011-12). During 2nd
year (2012-13), grain yield was 1227 kg ha-1 in control plots whereas it was 2324 kg ha-1
(89.4% higher) in plots having treatment (N 60 kg + FYM 20 Mg ha-1). Combined data for
both the years showed that grain yield increased from 1188 (control) to 2218 kg ha-1 (86.7%
higher) (N 60 kg + FYM 20 Mg ha-1).
69
Comparison of light factor in all the systems under observation (open field, Acacia-
based and Eucalyptus-based systems), showed that grain yield was significantly affected in
all the systems. Grain yield exhibited decreasing trend from 2742 kg ha-1 (open field) to 2100
kg ha-1 (23.4% lower) in Acacia-based and 1788 kg ha-1 (34.8%lower) in Eucalyptus-based
agroforestry system.
Comparison of soil fertility in all three systems under study i.e., open field, Acacia-
based and Eucalyptus-based systems, revealed that grain yield gradually increased with
application of soil amendments in all the systems. A progressive increase in grain yield was
recorded from 1655 (no amendment) to 2632 kg ha-1 (59% higher) (N 60 kg + FYM 20 Mg
ha-1).
70
Table 4.7 Effect of fertilizer application on wheat grain yield (kg ha-1) grown in open field, Acacia-based and Eucalyptus-based
agroforestry systems.
Treatments Open field
(PAR 100%)
Acacia-based agroforestry
system (PAR 73±3%)
Eucalyptus-based agroforestry
system (PAR 64±3%)
Grand
Mean
Year-1 Year-II Mean Year-I Year-II Mean Year-I Year-II Mean
Control
(T0) 1611±31.8 1635±30.5 1623d 1337±42.8 1441±83.4 1389e 1149±72.9 1227±61.9 1188d 1655e
N 60 Kg ha-1
(T1) 2468±38.2 2516±63.2 2492d 1903±65.6 2089±96.5 1996d 1651±83.9 1795±55.5 1723c 2070d
N 120 Kg ha-1
(T2) 2997±63.4 2963±51.4 2980b 2286±110 2404±151 2345b 1906±175 2078±76.2 1992b 2439b
FYM 20 Mg ha-1
(T3) 2687±58.5 2761±53.8 2724c 2138±94.2 2294±129 2216c 1818±138 1818±138 1818c 2252c
N 60 Kg + FYM
20 Mg ha-1 (T4) 3087±82.1 3157±56.1 3122a 2428±117 2682±172 2555a 2112±116 2324±70.4 2218a 2631a
Mean
2722.2 2760.8 2018.4 2182 1727.2 1848.4
2742 A 2100 B 1788 C
Means values followed by different letter(s) in each category are statistically different using least significantly difference (LSD) test at 5% level of probability.
71
4.1.1.8 Straw yield
The results of straw yield (Table 4.8) showed significant interactive effect of varying
levels of nitrogen and farm manure on straw yield of wheat in open field, Acacia-based and
Eucalyptus based alley cropping systems with different light intensity regimes. These results
indicated that straw yield in each plot increased with increase in fertility status in all the
systems (open and agroforestry systems).
In open field conditions, straw yield was 2644 kg ha-1 in control plots (no
amendment) whereas it was 4815 kg ha-1 (82.1% higher) in plots applied with treatment (N
60 kg + FYM 20 Mg ha-1) in 1st year of experimentation (2011-12). During 2nd year (2012-
13), straw yield was 2714 kg ha-1 in control plots whereas it was 4853 kg ha-1 (78.8% higher)
in plots applied with treatment (N 60 kg + FYM 20 Mg ha-1). Combined data for both the
years showed that straw yield increased from 2679 (control) to 4834 kg ha-1 (80.4% higher)
(N 60 kg + FYM 20 Mg ha-1).
In Acacia-based agroforestry system, straw yield was 2309 kg ha-1 in control plots (no
amendment) whereas it was 4083 kg ha-1 (76.8% higher) in plots applied with treatment
(FYM 20 Mg + N 60 kg ha-1) in 1st year of experimentation (2011-12). During 2nd year
(2012-13), straw yield was 2364 kg ha-1 in control plots whereas it was 4293 kg ha-1 (81.6%
higher) in plots having treatment (N 60 kg + FYM 20 Mg ha-1). Combined data for both the
years showed that straw yield increased from 2336 (control) to 4188 kg ha -1 (79.3% higher)
(N 60 kg + FYM 20 Mg ha-1).
In Eucalyptus-based agroforestry system, straw yield was 1953 kg ha-1 in control
plots (no amendment) whereas it was 3378 kg ha-1 (73% higher) in plots applied with
treatment (N 60 kg + FYM 20 Mg ha-1) in 1st year of experimentation (2011-12). During 2nd
year (2012-13), straw yield was 2039 kg ha-1 in control plots whereas it was 3549 kg ha-1
(74.1% higher) in plots having treatment (N 60 kg + FYM 20 Mg ha-1). Combined data for
both the years showed that straw yield increased from 1996 (control) to 3463 kg ha-1 (73.5%
higher) (N 60 kg + FYM 20 Mg ha-1).
72
Comparison of light factor in all the systems under observation (open field, Acacia-
based and Eucalyptus-based systems), showed that straw yield was significantly affected in
all the systems. Straw yield showed decreasing trend from 4212 kg ha-1 (open field) to 3483
kg ha-1 (17.3% lower) in Acacia-based and 2911 kg ha-1 (30.9% lower) in Eucalyptus-based
agroforestry system.
Comparison of soil fertility in all three systems under study i.e., open field, Acacia-
based and Eucalyptus-based systems, revealed that straw yield gradually increased with
application of soil amendments in all the systems. A progressive increase in straw yield was
recorded from 2766 (no amendment) to 4162 kg ha-1 (50.5% higher) (N 60 kg + FYM 20 Mg
ha-1).
73
Table 4.8 Effect of fertilizer application on wheat straw yield (kg ha-1) grown in open field, Acacia-based and Eucalyptus-based
agroforestry systems.
Treatments Open field
(PAR 100%)
Acacia-based agroforestry
system (PAR 73±3%)
Eucalyptus-based agroforestry
system (PAR 64±3%)
Grand
Mean
Year-1 Year-II Mean Year-I Year-II Mean Year-I Year-II Mean
Control
(T0) 2644±55 2714±74 2679d 2309±65.7 2364±133 2336e 1953±134 2039±131 1996d 2766d
N 60 Kg ha-1
(T1) 4054±64 4095±110 4074c 3200±115 3386±152 3293d 2749±161 2920±65 2834c 3400c
N 120 Kg ha-1
(T2) 4750±92 4816±75.2 4783a 3525±168 3757±223 3641c 2891±285 3273±115 3082b 3835b
FYM 20 Mg ha-1
(T3) 4413±89 4395±63.5 4404b 3963±182 3956±213 3959b 3119±244
3245
±120 3182b 3848b
N 60 Kg + FYM
20 Mg ha-1 (T4) 4815±116 4853±37.3 4834a 4083±208 4293±244 4188a 3378±218 3549±109 3463a 4162a
Mean
4391 4434 3416 3551 2818 3005
4412A 3483B 2911C
Means values followed by different letter(s) in each category are statistically different using least significantly difference (LSD) test at 5% level of probability.
74
4.1.1.9 Aggregate biomass (Biological yield)
The results of biological yield (Table 4.9) showed significant interactive effect of
varying levels of nitrogen and farm manure on straw yield of wheat in open field, Acacia-
based and Eucalyptus-based alley cropping systems with different light intensity regimes.
These results indicated that biological yield of experimental plots increased with increase in
fertility status in all the systems (open and agroforestry systems).
In open field conditions, biological yield was 4255 kg ha-1 in control plots (no
amendment) whereas it was 7902 kg ha-1 (85.7% higher) in plots applied with treatment (N
60 kg + FYM 20 Mg ha-1) in 1st year of experimentation (2011-12). During 2nd year (2012-
13), biological yield was 4349 kg ha-1 in control plots whereas it was 8010 kg ha-1 (84.2%
higher) in plots applied with treatment (N 60 kg + FYM 20 Mg ha-1). Combined data for
both the years showed that biological yield increased from 4302 (control) to 7956 kg ha -1
(84.9% higher) (N 60 kg + FYM 20 Mg ha-1).
In Acacia-based agroforestry system, biological yield was 3646 kg ha-1 in control
plots (no amendment) whereas it was 6511 kg ha-1 (78.6% higher) in plots applied with
treatment (FYM 20 Mg + N 60 kg ha-1) in 1st year of experimentation (2011-12). During 2nd
year (2012-13), biological yield was 3805 kg ha-1 in control plots whereas it was 6975 kg ha-1
(83.3% higher) in plots having treatment (N 60 kg + FYM 20 Mg ha-1). Combined data for
both the years showed that biological yield increased from 3725 (control) to 6743 kg ha -1
(81% higher) (N 60 kg + FYM 20 Mg ha-1).
In Eucalyptus-based agroforestry system, biological yield was 3102 kg ha-1 in control
plots (no amendment) whereas it was 5483 kg ha-1 (76.8% higher) in plots applied with
treatment (N 60 kg + FYM 20 Mg ha-1) in 1st year of experimentation (2011-12). During 2nd
year (2012-13), biological yield was 3266 kg ha-1 in control plots (no amendment) whereas it
was 5873 kg ha-1 (79.8% higher) in plots having treatment (N 60 kg + FYM 20 Mg ha-1).
Combined data for both the years showed that biological yield increased from 3184 (control)
to 5678 kg ha-1 (78.3% higher) (N 60 kg + FYM 20 Mg ha-1).
75
Comparison of light factor in all the systems under observation (open field, Acacia-
based and Eucalyptus-based systems), showed that biological yield was significantly affected
in all the systems. Biological yield exhibited decreasing trend from 7154 kg ha-1 (open field)
to 5583 kg ha-1 (22% lower) in Acacia-based and 4713 kg ha-1 (34.1% lower) in Eucalyptus-
based agroforestry system.
Comparison of soil fertility in all three systems under study i.e., open field, Acacia-
based and Eucalyptus-based systems, revealed that biological yield gradually increased with
application of soil amendments in all the systems. A progressive increase in biological yield
was recorded from 4422 (no amendment) to 6792 kg ha-1 (53.6% higher) (N 60 kg + FYM 20
Mg ha-1).
76
Table 4.9 Effect of fertilizer application on biological yield (kg ha-1) of wheat grown in open field, Acacia-based and
Eucalyptus-based agroforestry systems.
Treatments Open field
(PAR 100%)
Acacia-based agroforestry
system (PAR 73±3%)
Eucalyptus-based agroforestry
system (PAR 64±3%)
Grand
Mean
Year-1 Year-II Mean Year-I Year-II Mean Year-I Year-II Mean
Control
(T0) 4255±85.5 4349±103 4302d 3646±107 3805±216 3725d 3102±207 3266±192 3184d 4422d
N 60 Kg ha-1
(T1) 6522±101 6611±172 6566c 5103±177 5475±247 5289c 4400±244 4715±118 4557c 5471c
N 120 Kg ha-1
(T2) 7747±154 7779±125 7763a 5811±276 6161±368 5986b 4797±459 5351±189 5074b 6274b
FYM 20 Mg ha-1
(T3) 7105±147 7156±116 7130b 6101±276 6250±342 6175b 4937±381 5207±203 5072b 6126b
N 60 Kg + FYM
20 Mg ha-1 (T4) 7902±198 8010±93 7956a 6511±326 6975±415 6743a 5483±332 5873±176 5678a 6792a
Mean
7114 7195 5434 5733 4544 4882
7154A 5583B 4713C
Means values followed by different letter(s) in each category are statistically different using least significantly difference (LSD) test at 5% level of probability.
77
4.1.1.10 Harvest Index
The results of harvest index percentage (Table 4.10) showed significant interactive
effect of varying levels of nitrogen and farm manure on harvest index percentage of wheat in
open field, Acacia-based and Eucalyptus based alley cropping systems with different light
intensity regimes. These results indicated that harvest index percentage in experimental plots
increased with increase in fertility status in all the systems (open and agroforestry systems).
In open field conditions, harvest index was 37.7% in control plots (no amendment)
whereas it was 39 % (3.4% higher) in plots applied with treatment (N 60 kg + FYM 20 Mg
ha-1) in 1st year of experimentation (2011-12). During 2nd year (2012-13), harvest index was
37.5% in control (no amendment), whereas it was 39.4% (5.1% higher) in plots having
treatment (N 60 kg + FYM 20 Mg ha-1). Combined data for both the years showed that
harvest index increased from 37.6% (control) to 39.2% (4.3% higher) (N 60 kg + FYM 20
Mg ha-1).
In Acacia-based agroforestry system, harvest index was 36.7% in control plots (no
amendment) whereas it was 37.3% (1.6% higher) in plots applied with treatment (FYM 20
Mg + N 60 kg ha-1) in 1st year of experimentation (2011-12). During 2nd year (2012-13),
harvest index was 37.8% in control plots whereas it was 38.4% (1.6% higher) in plots having
treatment (N 60 kg + FYM 20 Mg ha-1). Combined data for both the years showed that
harvest index increased from 37.3% (control) to 37.8% (1.3% higher) (N 60 kg + FYM 20
Mg ha-1).
In Eucalyptus-based agroforestry system, harvest index was 37% in control plots (no
amendment) whereas it was 38.4% in plots applied with treatment (3.8% higher) (N 60 kg +
FYM 20 Mg ha-1) in 1st year of experimentation (2011-12). During 2nd year (2012-13),
harvest index was 37.6% in control plots whereas it was 39.5% (5.1% higher) in plots having
treatment (N 60 kg + FYM 20 Mg ha-1). Combined data for both the years showed that
harvest index increased from 37.3% (control) to 39% (4.6% higher) (N 60 kg + FYM 20 Mg
ha-1).
78
Comparison of light factor in all the systems under observation (open field, Acacia-
based and Eucalyptus-based systems); showed that harvest index was significantly affected
between open field and Acacia-based agroforestry systems whereas it was non-significant
between open field and Eucalyptus based systems. Biological yield exhibited decreasing
trend from 38.3% (open field) to 37.6% (1.8% lower) in Acacia-based and 38.1% (0.5%
lower) in Eucalyptus-based agroforestry system.
Comparison of soil fertility in all three systems under study i.e., open field, Acacia-
based and Eucalyptus-based systems, revealed that harvest index percentage gradually
increased with application of soil amendments in all the systems. A progressive increase in
harvest index was recorded from 37.4% (no amendment) to 38.7% (3.5% higher) (N 60 kg +
FYM 20 Mg ha-1).
79
Table 4.10 Effect of fertilizer application on harvest index percentage grown in open field, Acacia-based and Eucalyptus-based
agroforestry systems.
Treatments Open field
(PAR 100%)
Acacia-based agroforestry
system (PAR 73±3%)
Eucalyptus-based agroforestry
system (PAR 64±3%)
Grand
Mean
Year-1 Year-II Mean Year-I Year-II Mean Year-I Year-II Mean
Control
(T0) 37.7±0.12 37.5±0.18 37.6c 36.7±0.21 37.8±0.20 37.3c 37.0±0.14 37.6±0.35 37.3c 37.4c
N 60 Kg ha-1
(T1) 37.8±0.09 38.1±0.15 37.9c 37.3±0.31 38.1±0.26 37.7b 37.5±0.22 38.0±0.28 37.8b 37.8c
N 120 Kg ha-1
(T2) 38.6±0.14 38.1±0.11 38.4b 39.3±0.12 39.0±0.45 39.2a 39.7±0.27 38.8±0.25 39.3a 38.9a
FYM 20 Mg ha-1
(T3) 37.8±0.13 38.6±0.16 38.2bc 35.0±0.11 36.7±0.22 35.8d 36.8±0.10 37.6±0.27 37.2c 37.1c
N 60 Kg + FYM
20 Mg ha-1 (T4) 39.0±0.10 39.4±0.24 39.2a 37.3±0.11 38.4±0.27 37.8b 38.4±0.29 39.5±0.26 39.0a 38.7b
Mean
38.2 38.3 37.1 38.0 37.9 38.3
38.3A 37.6B 38.1A
Means values followed by different letter(s) in each category are statistically different using least significantly difference (LSD) test at 5% level of
probability.
80
4.1.2 Tree growth and wood production
4.1.2.1 Tree bole volume
The results of tree bole volume (Table 4.11) present interactive effect of varying
levels of nitrogen and farm yard manure on the tree growth in Acacia and Eucalyptus based
alley cropping systems. These results indicated that tree bole volume increased with the
increase in soil fertility status of agroforestry systems.
In Acacia-based agroforestry system, bole volume of trees increased from 17.1 to
19.2 m3 ha-1 (12.3% higher) in control plots (no amendment) during 1st year of
experimentation (2011-12). In 2nd (2012-13), bole volume of trees increased from 19.2 to
21.6 m3 ha-1 (12.5% higher) in control plots. In case, where application of soil amendments
(N 60 kg + FYM 20 Mg ha-1) was made, bole volume of trees increased from 19 to 21.6 m3
ha-1 (13.7% higher) during 1st year (2011-12). In 2nd year (2012-13), bole volume of trees
increased from 21.6 to 24.4 m3 ha-1 (13% higher). In case of sole tree plantation of A.
nilotica, bole volume increased from 17.5 to 19.8 m3 ha-1 (13.1% higher) during 1st year
(2011-12) while in 2nd year (2012-13), it increased from 19.8 to 21.4 m3 ha-1 (8.1% higher).
In case of Eucalyptus-based agroforestry system, bole volume of trees increased from
26.7 to 31.7 m3 ha-1 (18.7% higher) in control plots (no amendment) during 1st year (2011-
12). In 2nd year (2012-13), bole volume of trees increased from 31.7 to 37.1 m3 ha-1 (17%
higher) in control treatment. In experimental plots, where application of soil amendment (N
60 kg + FYM 20 Mg ha-1) was made, bole volume of trees increased from 26.4 to 32.7 m3
ha-1 (23.9% higher) during 1st year (2011-12). In 2nd year (2012-13), bole volume of trees
increased from 32.7 to 39.3 m3 ha-1 (20.2% higher) in these treatments. In case of sole tree
plantation of E. camaldulensis, bole volume of trees increased from 25.9 to 31.0 m3 ha-1
(19.7% higher) during 1st year (2011-12). In 2nd year (2012-13), bole volume of trees
increased from 31.0 to 36.9 m3 ha-1 (19% higher) in the treatment plots.
Overall comparison of fertility factor in these systems showed that bole volume was
improved with application of soil amendments in agroforestry systems as compared to
control (no amendment) /sole plantations of each tree species.
81
Table 4.11 Effect of amendments on bole volume (m3 ha-1) grown in sole field, Acacia-
based and Eucalyptus-based agroforestry systems.
Treatments
Bole Volume (m3 ha-1)
Acacia nilotica Eucalyptus camaldulensis
2011 2012 2013 2011 2012 2013
Control
(T0)
17.1±2.93
19.2±3.24
21.6±3.96
26.7±3.06
31.7±3.79
37.2±4.78
N 60 Kg ha-1
(T1)
16.5±3.04
18.9±3.35
21.3±3.81
23.9±1.97
29.1±2.34
35.6±2.90
N 120 Kg ha-1
(T2)
17.0±0.95
19.3±0.82
21.8±1.98
24.4±1.95
30.9±2.14
36.7±2.62
FYM 20 Mg ha-1
(T3)
17.4±2.35
19.8±2.57
22.4±2.96
24.2±2.91
29.9±3.04
36.4±3.78
N 60 Kg + FYM 20
Mg ha-1 (T4)
16.0±2.73
18.6±2.96
21.4±3.36
25.4±2.59
31.7±3.10
38.3±3.71
Sole Plantation 17.5±1.13
19.8±1.14
21.4±1.47
25.9±2.07
31.0±2.43
36.9±3.03
82
4.1.2.2 Mean Annual Increment in wood production
The results of mean annual increment in wood production (Table 4.12) showed
significant interactive effect of varying levels of nitrogen and farm yard manure on tree
growth in Acacia-based and Eucalyptus-based alley cropping systems. Tree mean annual
increment (MAI) in wood volume increased with increase in fertility status in agroforestry
systems.
In Acacia-based agroforestry system, current annual increment (CAI) in bole volume
of trees was recorded as 2.21 m3 ha-1 yr-1 during 1st year of experimentation (2011-12) in
control (no amendment) whereas it was 2.39 m3 ha-1 (8.1% higher) during 2nd year (2012-13).
Thus, mean annual increment (MAI) was 2.30 m3 ha-1 yr-1 in control treatment.
Generally, there was a cumulative trend in mean annual increment (MAI) in bole
volume of trees (A. nilotica) with application of fertilizer amendments. In case of application
of soil amendments (N 60 kg + FYM 20 Mg ha-1), current annual increment (CAI) in bole
volume of trees was 2.57 m3 ha-1 yr-1 during 1st year (2011-12). In 2nd year (2012-13), current
annual increment (CAI) in bole volume of trees was 2.81 m3 ha-1 yr-1 (9.3% higher). So,
mean annual increment (MAI) was 2.69 m3 ha-1 yr-1 in the experimental plots receiving
fertility treatment (N 60 kg + FYM 20 Mg ha-1).
In case of sole tree plantation, current annual increment (CAI) in bole volume was
2.26 m3 ha-1 yr-1 during 1st year (2011-12). In 2nd year (2012-13), CAI in bole volume of trees
was 2.31 m3 ha-1 yr-1 (2.2% higher). Thus, mean annual increment (MAI) was 2.29 m3 ha-1
yr-1 in sole plantation.
In Eucalyptus-based agroforestry system, current annual increment (CAI) in bole
volume of trees was 4.97 m3 ha-1 yr-1 in control treatment during 1st year of experimentation
(2011-12). In 2nd (2012-13), current annual increment (CAI) in bole volume of trees was
5.48 m3 ha-1 yr-1 (10.3% higher) in control treatment. In this way, net mean annual increment
(MAI) was 5.23 m3 ha-1 yr-1 in control treatment plots.
83
It was observed that there was an increasing trend in the mean annual increment
(MAI) in bole volume of trees (Eucalyptus camaldulensis) by the application of fertilizer
amendments. In case of application of soil amendments (N 60 kg + FYM 20 Mg ha-1),
current annual increment (CAI) in bole volume of trees was 6.31 m3 ha-1 yr-1 during 1st year
(2011-12). In 2nd year (2012-13), current annual increment (CAI) in bole volume of trees
was 6.63 m3 ha-1(5.1% higher). So, mean annual increment (MAI) was 6.47 m3 ha-1 yr-1 in
such treatment.
In sole Eucalyptus tree plantation system, current annual increment (CAI) in bole
volume was 5.13 m3 ha-1 yr-1 during 1st year (2011-12), whereas, in 2nd year (2012-13),
current annual increment (CAI) in bole volume of trees was 5.88 m3 ha-1 yr-1 (14.6% higher).
Mean annual increment (MAI) was 5.51 m3 ha-1 yr-1 in sole plantation plots.
84
Table 4.12 Effect of amendments on mean annual increment (m3 ha-1 yr-1) in wood production of trees grown in sole field,
Acacia-based and Eucalyptus-based agroforestry systems.
Treatment
m3 ha-1 yr-1
Acacia nilotica E. camaldulensis
CAI
(2011-12)
CAI
(2012-13)
MAI Annual
wood
addition
(Kg)
CAI
(2011-12)
CAI
(2012-13)
MAI Annual
wood
addition
(Kg)
Control(To)
2.21 2.39 2.30c 1861 4.97 5.48 5.23e 3562
N 60 kg ha-1 (T1)
2.30 2.41 2.36bc 1909 5.26 6.52 5.89c 4011
N 120 kg ha-1 (T2)
3.31 2.46 2.38bc 1925 5.76 6.57 6.16b 4195
FYM 20 Mg+N 30 kg ha-1 (T3)
2.38 2.54 2.46ab 1990 5.71 6.44 6.07b 4134
N 60 Kg + FYM 20 Mg ha-1 (T4) 2.57 2.81 2.69a 2176 6.31 6.63 6.47a 4406
Sole Tree Block 2.26 2.31 2.29c 1853 5.13 5.88 5.51d 3752
Mean 2.51 2.47 2.49 5.52 6.25 5.89
Means values followed by different letter(s) in each category are statistically different using least significantly difference (LSD) test at 5% level of probability.
85
4.1.3 Annual biomass productivity of different systems
The results of annual biomass productivity (Table 4.13) showed significant
interactive effect of varying levels of nitrogen and farm manure on annual biomass
productivity of wheat and/or wood in open field, Acacia and Eucalyptus based alley cropping
systems with different regimes of light intensity. These results indicate increased annual
biomass productivity with increase in fertility status in all the systems (open and agroforestry
systems).
In open field conditions (sole wheat cropping), annual biomass productivity was 4302
kg ha-1 yr-1 in control plots (no amendment) which increased significantly with application of
different amendments and it was 7956 kg ha-1 yr-1 in plots applied with treatment (N 60 kg +
FYM 20 Mg ha-1) showing 84.9% increase as compared to the respective control.
In Acacia-based agroforestry system, the lowest biomass productivity of wheat
component was 3725 kg ha-1 yr-1, whereas; woody component was 1861 kg ha-1 yr-1 in
control treatment plots (no amendment). Hence, the annual biomass productivity attained as
5586 kg ha-1 yr-1. Biomass productivity of both components of the system increased
progressively by the application of different levels of amendments. The highest biomass
productivity of wheat component was 6743 kg ha-1 yr-1 whereas that of woody component
was 2176 kg ha-1 yr-1 in treatment plots (N 60 kg + FYM 20 Mg ha-1). Hence aggregate
biomass productivity was recorded as 8919 kg ha-1 yr-1 (59.7% higher). In case of sole
plantation of A. nilotica, biomass productivity was 1853 kg ha-1 yr-1.
In Eucalyptus-based agroforestry system, the lowest biomass productivity of wheat
component was 3184 kg ha-1 yr-1, whereas, woody component was 3562 kg ha-1 yr-1 in
control plots (no amendment). Hence, aggregate biomass productivity was 6764 kg ha-1 yr-1.
Biomass productivity of both the components of the system increased progressively with the
application of different levels of amendments. The highest biomass productivity of wheat
component was 5678 kg ha-1 yr-1, whereas that of woody component was 4406 kg ha-1 yr-1 in
treatment plots (N 60 kg + FYM 20 Mg ha-1). Hence, aggregate biomass productivity was
recorded as 10084 kg ha-1 yr-1 (49.1% higher). In case of sole plantation of Eucalyptus
camaldulensis, biomass productivity was 3752 kg ha-1 yr-1.
86
It is evident that in open field conditions, the lowest biomass productivity of 4302 kg-
1 ha-1 yr-1 was achieved in wheat plots grown in open field, whereas the highest biomass
productivity (7956 kg-1 ha-1 yr-1) was obtained in plots applied with the treatment (N 60 kg +
FYM 20 Mg ha-1).
In Acacia-based agroforestry systems, the lowest biomass productivity of 5586 kg-1
ha-1 yr-1 was gained in wheat grown in open field, whereas the highest biomass productivity
(8919 kg-1 ha-1 yr-1) was recorded in plots where treatment (N 60 kg + FYM 20 Mg ha-1) was
applied. In sole plantations of A. nilotica, biomass productivity was 1853 kg-1 ha-1 yr-1.
In Eucalyptus-based agroforestry systems, the lowest biomass productivity (6764 kg-1
ha-1 yr-1) was achieved in wheat plots grown in open field whereas the highest biomass
productivity (10084 kg-1 ha-1 yr-1) was obtained in plots applied with treatment (N 60 kg +
FYM 20 Mg ha-1). In sole plantations of E. camaldulensis, biomass productivity was 3752
kg-1 ha-1 yr-1.
87
Table 4.13 Effect of amendments on aggregate biomass productivity (kg ha-1 yr-1) of sole plantation, Acacia-based and
Eucalyptus-based agroforestry systems.
Treatments
Biomass production (kg ha-1 yr-1)
Open field
(Sole cropping)
Acacia-based
agroforestry system
Eucalyptus-based
agroforestry system
Wheat Wood Total Wheat Wood Total Wheat Wood Total
Control (To)
4302 - 4302d 3725 1861 5586d
3184
3562 6764d
N 60 kg ha-1 (T1)
6566 - 6566c 5289 1909 7198c
4557
4011 8568c
N 120 kg ha-1 (T2)
7763 - 7763a 5986 1925 7911b
5074
4195 9269b
FYM 20 Mg +
N 30 kg ha-1 (T3)
7130 - 7130b 6175 1990 8165b 5072
4134 9206b
N 60 kg + FYM 20 Mg
ha-1 (T4)
7956 - 7956a 6743 2176 8919a 5678
4406 10084a
Sole Plantation of tree
(no amendment) NA NA NA - 1853 1853e - 3752 3752e
Means values followed by different letter(s) in each category are statistically different using least significantly difference (LSD) test at 5% level of probability.
88
4.1.4 Variations in soil chemical properties under sole and alley cropping systems
Cultivation of plants either in open field or in agroforestry systems strongly
influences chemical properties of soil due to root physical/mechanical action, root exudation,
change in evapotranspiration pattern and nutrient recycling by plants. Among these chemical
properties, pH, electrical conductivity (EC), and sodium adsorption ratio (SAR) are of main
concern from soil amelioration point of view in agroforestry systems established in salt-
affected soils. Results obtained for above mentioned soil chemical parameters from the
present study are presented in following sections.
4.1.4.1 Soil pH
Data regarding pH of soil profile (0-150 cm) in open field, Acacia and Eucalyptus
based alley cropping systems is shown in Fig. 3 and described in tables 4.14 to 4.16. In all
the systems (open field, Acacia-based and Eucalyptus-based systems), pre-experimentation
analysis of soil properties regarding pH values showed difference at various depths (0-15, 15-
30, 30-60, 60-90, 90-120 and 120-150 cm) in soil profile.
In open field system, soil pH (Table 4.14) recorded at the initiation of study was 8.47
in control (no amendment) at 0-15 cm. With the passage of time, soil pH increased to 8.65
after cultivation of wheat for two successive years. Similarly, soil pH at the depth of 15-30
cm increased from 8.52 to 8.61 with cultivation of wheat. Soil pH also showed variation with
application of amendments and the highest reduction was found in upper layer (0-15 cm) in
treatment plots applied with treatment (N 60 kg +FYM 20 Mg ha-1). Variation in soil pH in
deep layers from 30 to 150 cm as affected with application of different amendments is shown
in table. Generally pH increased in deeper layers due to leaching of salts from the upper
layers.
In Acacia based systems, soil pH (Table 4.15) in respective control (no amendment)
at the start of experimentation was 8.55 (0-15 cm) which decreased to 8.49 with cultivation
of wheat for two successive years. At the depth of 15-30 cm, soil pH was 8.54 which
decreased to 8.47 with cultivation of wheat. Soil pH also showed variation with application
of amendments and the highest reduction was observed in upper layers (0-15 and 15-30 cm)
in treatment plots applied with treatment (N 60 kg + FYM-20 Mg ha-1 ). In case of sole
plantation, minor reduction was found in upper 0-15 and 15-30 cm, respectively. Variation in
89
soil pH in deep layers from 30 to 150 cm as affected with application of different
amendments is shown in table. Generally pH increased in deeper layers due to leaching of
salts from the upper layers.
In Eucalyptus-based systems, soil pH (Table 4.16) in their respective control
treatment (no amendment) at the start of experimentation was 8.56 (0-15 cm) which
decreased to 8.53 with cultivation of wheat for two successive years. At the depth of 15-30
cm, pH was 8.55 which decreased to 8.51 with the cultivation of wheat. Soil pH also showed
variation with application of amendments and the highest reduction was found in upper
layers (0-15, 15-30 cm, respectively) in treatment plots (N 60 kg + FYM-20 Mg ha-1 ). In
case of sole plantation, soil pH was slightly reduced in upper (0-15 cm) and lower (15-30
cm) soil layer. Variations in soil pH in other deep layers from 30 to 150 cm as affected with
application of different amendments are shown in table. Generally, pH increased in deeper
layers possibly due to leaching of salts from the upper layers.
In agroforestry systems, more reduction in pH was found in Acacia based systems as
compared to Eucalyptus-based systems. Further, application of farm yard manure alone or in
combination with nitrogen also affected pH in both the systems to varying extent and more
prominently in Acacia-based systems.
90
Figure 3. Effect of different soil amendments on soil pH under open field, Acacia- and
Eucalyptus-based alley cropping systems
-4
-2
0
2
4
T0 T1 T2 T3 T4 T5
0 to 15 cm
-2
-1
0
1
2
3
T0 T1 T2 T3 T4 T5
60 to 90 cm
-3
-2
-1
0
1
2
T0 T1 T2 T3 T4 T5
16 to 30 cm
-1
0
1
2
3
T0 T1 T2 T3 T4 T5
90 to 120 cm
-2
-1
0
1
2
T0 T1 T2 T3 T4 T5
30 to 60 cm
Open crop field Acacia based alley
Eucalyptus-based alley
-2
0
2
4
T0 T1 T2 T3 T4 T5
120 to 150 cm
Open crop field Acacia based alley
Eucalyptus-based alley
91
Table 4.14 Effect of amendments on soil pH in open field (sole cropping).
Treatment Depth
(cm)
Open crop field
Nov
2011
May
2012
Nov
2012
May
2013
% change
over initial
value
Control (To)
0-15 8.47 8.76 8.74 8.65 2.13
15-30 8.52 8.54 8.53 8.61 1.06
30-60 8.43 8.51 8.47 8.46 0.35
60-90 8.39 8.46 8.36 8.48 1.06
90-120 8.41 8.54 8.48 8.57 1.90
120-150 8.31 8.43 8.37 8.46 1.81
N 60 kg ha-1 (T1)
0-15 8.58 8.56 8.57 8.64 0.70
15-30 8.53 8.61 8.57 8.57 0.47
30-60 8.47 8.54 8.52 8.51 0.47
60-90 8.32 8.52 8.43 8.47 1.80
90-120 8.47 8.57 8.52 8.64 2.01
120-150 8.39 8.53 8.45 8.57 2.15
N 120 kg ha-1 (T2)
0-15 8.62 8.58 8.67 8.65 0.35
15-30 8.43 8.36 8.4 8.44 0.12
30-60 8.42 8.41 8.45 8.47 0.59
60-90 8.34 8.45 8.39 8.49 1.80
90-120 8.27 8.33 8.31 8.39 1.45
120-150 8.29 8.37 8.33 8.44 1.81
FYM 20 Mg ha-1 (T3)
0-15 8.47 8.44 8.44 8.43 -0.47
15-30 8.52 8.47 8.51 8.44 -0.94
30-60 8.57 8.49 8.54 8.47 -1.17
60-90 8.34 8.49 8.43 8.56 2.64
90-120 8.26 8.39 8.33 8.47 2.54
120-150 8.31 8.49 8.42 8.56 3.01
N 60 kg + FYM20 Mg
ha-1 (T4)
0-15 8.57 8.52 8.54 8.47 -1.17
15-30 8.44 8.41 8.39 8.33 -1.30
30-60 8.44 8.53 8.51 8.57 1.54
60-90 8.16 8.29 8.21 8.36 2.45
90-120 8.21 8.33 8.32 8.41 2.44
120-150 8.21 8.35 8.26 8.29 0.97
92
Table 4.15 Effect of amendments on soil pH in Acacia based alley cropping systems
Treatment
Depth
(cm)
Acacia based alley cropping system
Nov
2011
May
2012
Nov
2012
May
2013
% change
over initial
value
Control (To)
0-15 8.55 8.57 8.51 8.49 -0.70
15-30 8.54 8.63 8.55 8.47 -0.82
30-60 8.57 8.61 8.57 8.54 -0.35
60-90 8.53 8.60 8.68 8.65 1.41
90-120 8.68 8.77 8.74 8.81 1.50
120-150 8.63 8.72 8.75 8.85 2.55
N 60 kg ha-1 (T1)
0-15 8.49 8.51 8.47 8.45 -0.47
15-30 8.52 8.59 8.51 8.49 -0.35
30-60 8.59 8.54 8.49 8.54 -0.58
60-90 8.64 8.71 8.68 8.75 1.27
90-120 8.68 8.74 8.77 8.85 1.96
120-150 8.77 8.84 8.81 8.88 1.25
N 120 kg ha-1 (T2)
0-15 8.47 8.49 8.46 8.44 -0.35
15-30 8.48 8.54 8.58 8.42 -0.71
30-60 8.52 8.54 8.56 8.57 0.59
60-90 8.53 8.64 8.57 8.62 1.06
90-120 8.31 8.34 8.37 8.50 2.29
120-150 8.32 8.41 8.38 8.43 1.32
FYM 20 Mg ha-1 (T3)
0-15 8.51 8.46 8.41 8.37 -1.65
15-30 8.64 8.61 8.63 8.55 -1.04
30-60 8.59 8.54 8.52 8.50 -1.05
60-90 8.46 8.65 8.57 8.62 1.89
90-120 8.61 8.75 8.64 8.71 1.16
120-150 8.76 8.78 8.82 8.83 -0.80
N 60 kg + FYM 20
Mg ha-1 (T4)
0-15 8.58 8.46 8.37 8.31 -3.16
15-30 8.52 8.43 8.39 8.31 -2.46
30-60 8.57 8.53 8.51 8.46 -1.28
60-90 8.58 8.66 8.63 8.56 -0.23
90-120 8.58 8.69 8.62 8.72 1.63
120-150 8.61 8.73 8.70 8.78 1.97
Pure Tree Plantation
(Acacia nilotica)
0-15 8.51 8.46 8.4 8.43 -0.94
15-30 8.63 8.61 8.63 8.58 -0.58
30-60 8.57 8.61 8.57 8.54 -0.35
60-90 8.52 8.53 8.47 8.43 -1.06
90-120 8.61 8.65 8.61 8.54 -0.81
120-150 8.57 8.61 8.64 8.71 1.63
93
Table 4.16 Effect of amendments on soil pH in Eucalyptus-based alley cropping systems.
Treatment Depth
(cm)
Eucalyptus based alley cropping system
Nov
2011
May
2012
Nov
2012
May
2013
% change
over initial
value
Control (To)
0-15 8.56 8.54 8.54 8.53 -0.35
16-30 8.55 8.57 8.51 8.51 -0.47
30-60 8.47 8.55 8.46 8.58 1.30
60-90 8.61 8.63 8.64 8.77 1.86
90-120 8.61 8.67 8.64 8.72 1.28
120-150 8.65 8.68 8.66 8.74 1.04
N 60 kg ha-1 (T1)
0-15 8.64 8.64 8.64 8.62 -0.23
16-30 8.46 8.29 8.27 8.44 -0.24
30-60 8.49 8.46 8.48 8.41 -0.94
60-90 8.37 8.45 8.39 8.50 1.55
90-120 8.61 8.62 8.66 8.67 0.70
120-150 8.52 8.58 8.54 8.61 1.06
N 120 kg ha-1 (T2)
0-15 8.59 8.55 8.55 8.55 -0.47
16-30 8.58 8.53 8.54 8.54 -0.47
30-60 8.62 8.54 8.59 8.57 -0.58
60-90 8.41 8.47 8.45 8.51 1.18
90-120 8.51 8.56 8.59 8.63 1.39
120-150 8.66 8.68 8.64 8.72 0.69
FYM 20 Mg ha-1 (T3)
0-15 8.51 8.47 8.49 8.45 -0.71
16-30 8.48 8.55 8.52 8.43 -0.59
30-60 8.42 8.57 8.47 8.38 -0.48
60-90 8.39 8.38 8.37 8.42 0.36
90-120 8.38 8.48 8.43 8.55 2.03
120-150 8.57 8.67 8.61 8.71 1.63
N 60 kg +FYM 20 Mg
ha-1 (T4)
0-15 8.54 8.51 8.47 8.44 -1.17
16-30 8.54 8.71 8.51 8.42 -1.41
30-60 8.64 8.57 8.58 8.56 -0.93
60-90 8.65 8.77 8.71 8.82 1.97
90-120 8.51 8.62 8.56 8.67 1.88
120-150 8.49 8.58 8.54 8.62 1.53
Pure Tree Plantation
(Eucalyptus
camaldulensis)
0-15 8.64 8.61 8.63 8.63 -0.12
16-30 8.62 8.46 8.52 8.59 -0.35
30-60 8.58 8.56 8.53 8.49 -1.05
60-90 8.77 8.73 8.71 8.71 -0.68
90-120 8.68 8.77 8.74 8.82 1.61
120-150 8.62 8.69 8.64 8.72 1.16
94
4.1.4.2 Soil electrical conductivity
Data regarding electrical conductivity (EC) of soil profile (0-150 cm) in open
field, Acacia-based and Eucalyptus-based alley cropping systems is Fig. 4 and described in
tables 4.17 to 4.19. In all the systems (open field, Acacia-based and Eucalyptus-based
systems), pre-experimentation analysis of soil electrical conductivity showed variation at
different depths (0-15, 15-30, 30-60, 60-90, 90-120 and 120-150 cm).
In open field system, pre-experimentation soil EC in control plots (no amendment)
was 12.86 dS m-1 (0-15 cm) which increased to 14.27 dS m-1 with cultivation of wheat for
two successive years (Table 4.17). Soil EC also showed variation with application of
amendments and the highest reduction was found in upper layer (0-15 cm) in plots applied
with N 60 kg +FYM 20 Mg ha-1. Variations in soil EC in deep layers from 30 to 150 cm as
affected with application of different amendments are shown in table. Generally, electrical
conductivity increased in deeper layers of soils due to leaching of salts from the surface.
In Acacia-based systems, soil EC in respective control plots (no amendment) at the
start of experimentation was 10.7 dS m-1 (0-15 cm) which decreased to 9.35 dS m-1 with
cultivation of wheat for two years (Table 4.18). At the depth of 15-30 cm, soil EC was 12.7
dS m-1 which decreased to 11.07 dS m-1 with cultivation of wheat. Soil EC also showed
variation with application of amendments and the highest reduction was found in upper
layers (0-15, 15-30 cm respectively) in treatment plots applied with N 60 kg + FYM-20 Mg
ha-1. In case of sole plantation, reduction in electrical conductivity was observed in upper 0-
15 and 15-30 cm, respectively. Variation in soil EC at depths up to 150 cm as affected with
application of different amendments as shown in table revealed that salts leached from the
soil surface to deeper layers of soil profile to different extent.
In Eucalyptus-based systems, pre-experimentation soil EC in respective control (no
amendment) was 12.3 dS m-1 (0-15 cm) which decreased to 11.3 dS m-1 with cultivation of
wheat for two successive years (Table 4.19). At the depth of 15-30 cm, soil EC was 12.7 dS
m-1 which decreased to 11.9 dS m-1 with cultivation of wheat. Soil EC also showed variation
with application of amendments and the highest reduction was observed in upper layers (0-
95
15, 15-30 cm, respectively) in treatment plots applied with treatment (N 60 kg + FYM-20
Mg ha-1 ). Variation in soil EC at other depths up to 150 cm as affected with application of
different amendments given in table showed that salts leached from the surface to deeper
layers of soil profile.
In case of sole plantation of A. nilotica and E. camaldulensis, minor reduction in EC
was observed in upper 0-15 and 15-30 cm, respectively. The restoration process was more
effective in A. nilotica as compared to E. camaldulensis plantations.
96
Figure 4. Effect of different soil amendments on soil electrical conductivity (EC) under
open field, Acacia- and Eucalyptus-based alley cropping systems
-30
-20
-10
0
10
20
T0 T1 T2 T3 T4 T5
0 to 15 cm
-10
0
10
20
30
T0 T1 T2 T3 T4 T5
60 to 90 cm
-30
-20
-10
0
10
20
T0 T1 T2 T3 T4 T5
16 to 30 cm
-10
0
10
20
30
T0 T1 T2 T3 T4 T5
90 to 120 cm
-50
0
50
T0 T1 T2 T3 T4 T5
30 to 60 cm
Open crop field Acacia based alley
Eucalyptus-based alley
-20
0
20
40
T0 T1 T2 T3 T4 T5
120 to 150 cm
Open crop field Acacia based alley
Eucalyptus-based alley
97
Table 4.17 Effect of amendments on soil electrical conductivity in sole cropping systems.
Treatment Depth
(cm)
Open crop field
Nov
2011
May
2012
Nov
2012
May
2013
% change over
initial value
Control (To)
0-15 12.86 13.84 12.76 14.27 10.96
16-30 11.71 12.79 13.61 12.87 9.91
30-60 12.36 14.28 12.37 13.26 7.28
60-90 12.37 11.36 10.84 12.85 3.88
90-120 11.27 15.31 14.39 13.26 17.66
120-150 11.87 14.29 13.29 13.29 11.96
N 60 kg ha-1 (T1)
0-15 11.76 10.55 13.55 13.02 10.71
16-30 10.58 12.36 12.98 12.22 15.50
30-60 12.85 13.85 11.83 13.94 8.48
60-90 12.31 11.37 12.08 14.04 14.05
90-120 13.75 14.87 11.87 14.84 7.93
120-150 14.56 14.97 15.67 15.37 5.56
N 120 kg ha-1 (T2)
0-15 10.26 10.79 12.55 11.76 14.62
16-30 11.76 12.53 13.07 13.34 13.44
30-60 12.35 14.79 12.37 14.28 15.63
60-90 14.56 15.97 13.56 15.97 9.68
90-120 16.23 15.68 16.82 16.97 4.56
120-150 14.55 14.73 15.29 15.37 5.63
FYM 20 Mg ha-1
(T3)
0-15 13.45 11.28 12.33 11.36 -15.54
16-30 14.11 12.55 14.37 12.31 -12.76
30-60 10.19 11.29 11.08 10.97 7.65
60-90 11.23 11.87 12.97 12.75 13.54
90-120 11.23 13.55 11.67 13.20 17.54
120-150 15.66 17.77 16.55 18.29 16.79
N 60 kg +FYM 20
Mg ha-1
(T4)
0-15 14.78 12.77 10.02 12.07 -18.34
16-30 14.28 12.38 13.27 11.07 -22.48
30-60 10.47 10.46 11.26 12.26 17.10
60-90 11.88 14.17 13.07 15.07 26.85
90-120 14.15 14.89 12.24 15.61 10.32
120-150 13.51 14.66 14.21 15.45 14.36
98
Table 4.18 Effect of amendments on soil electrical conductivity in Acacia-based alley
cropping systems.
Treatment Depth
(cm)
Acacia-based alley cropping systems
Nov
2011
May
2012
Nov
2012
May
2013
% change over
initial value
Control (To)
0-15 10.76 9.77 10.02 9.35 -13.10
16-30 12.76 11.26 11.69 11.07 -13.24
30-60 15.26 14.77 12.27 14.37 -5.83
60-90 12.95 16.92 14.19 16.42 26.80
90-120 15.27 18.66 16.04 19.84 29.93
120-150 16.48 19.37 18.08 19.79 20.08
N 60 kg ha-1 (T1)
0-15 14.11 12.55 14.37 12 -14.95
16-30 12.89 11.51 12.19 10.87 -15.67
30-60 12.56 11.29 13.29 10.84 -13.69
60-90 11.87 11.97 10.86 13.48 13.56
90-120 13.07 13.15 12.67 15.31 17.14
120-150 14.84 15.84 13.71 17.53 18.13
N 120 kg ha-1 (T2)
0-15 14.76 10.79 12.55 12.26 -16.94
16-30 13.22 12.36 12.98 10.58 -19.97
30-60 15.12 13.16 13.94 11.27 -25.46
60-90 12.35 13.50 14.87 15.36 24.37
90-120 15.97 17.56 16.58 19.15 19.91
120-150 15.87 17.26 16.34 18.75 18.15
FYM 20 Mg ha-1
(T3)
0-15 15.71 10.79 13.61 12.37 -21.26
16-30 12.75 11.86 10.55 9.87 -22.59
30-60 12.21 11.37 10.84 10.27 -15.89
60-90 11.82 13.54 12.53 15.31 29.53
90-120 15.45 16.72 14.82 18.42 19.22
120-150 17.76 18.55 16.59 20.41 14.92
N 60 kg +FYM 20
Mg ha-1 (T4)
0-15 12.26 10.46 11.26 9.47 -22.76
16-30 13.45 11.28 12.33 10.36 -22.97
30-60 14.28 12.25 12.65 11.84 -17.09
60-90 13.97 16.06 14.55 16.85 20.62
90-120 17.29 18.72 16.43 19.24 11.28
120-150 15.97 17.59 16.11 18.75 17.41
Pure Tree
Plantation (Acacia
nilotica)
0-15 13.02 10.55 13.55 11.76 -9.68
16-30 13.34 12.53 13.07 11.76 -11.84
30-60 15.27 13.87 14.27 12.55 -17.81
60-90 13.87 14.56 16.06 13.14 -5.26
90-120 16.76 15.49 17.83 15.34 -8.47
120-150 17.11 17.98 19.55 16.45 -3.86
99
Table 4.19 Effect of amendments on soil electrical conductivity (EC) in Eucalyptus-
based alley cropping systems.
Treatment
Depth
(cm)
Eucalyptus-based alley cropping systems
Nov
2011
May
2012
Nov
2012
May
2013
% change
over initial
value
Control (To)
0-15 12.36 11.26 11.69 11.37 -8.01
16-30 12.75 11.86 10.55 11.89 -6.75
30-60 10.94 12.07 11.28 12.91 18.01
60-90 12.49 12.38 11.24 14.55 16.49
90-120 15.21 16.54 17.67 17.59 15.65
120-150 16.87 17.59 15.24 18.55 9.96
N 60 kg ha-1 (T1)
0-15 13.45 11.28 12.33 11.86 -11.82
16-30 13.52 11.51 12.19 11.85 -12.35
30-60 13.89 12.27 11.83 11.37 -18.14
60-90 10.97 12.54 11.37 13.87 26.44
90-120 13.59 14.21 15.87 16.64 22.14
120-150 12.88 16.89 14.27 16.08 24.84
N 120 kg ha-1 (T2)
0-15 13.48 12.53 13.07 11.76 -12.76
16-30 10.76 9.77 10.02 9.35 -13.10
30-60 12.56 13.26 11.27 10.55 -16.00
60-90 12.37 13.57 14.56 15.46 24.98
90-120 14.78 18.56 16.37 19.56 28.91
120-150 18.55 21.21 19.87 22.44 20.97
FYM 20 Mg ha-1
(T3)
0-15 12.26 10.46 11.26 10.45 -14.76
16-30 14.11 12.55 14.37 12.48 -11.55
30-60 16.25 14.86 14.21 13.82 -14.95
60-90 13.89 16.21 14.37 17.88 28.73
90-120 17.23 20.76 18.37 22.89 27.05
120-150 15.94 18.77 17.54 20.85 17.18
N 60 kg +FYM
20 Mg ha-1 (T4)
0-15 14.76 10.79 12.55 12.26 -16.94
16-30 15.71 10.79 13.61 12.96 -17.50
30-60 15.36 14.21 13.88 12.81 -16.60
60-90 13.77 16.57 15.67 18.26 25.34
90-120 15.12 19.87 17.95 21.89 24.93
120-150 14.29 18.37 16.27 19.56 22.88
Pure Tree Plantation
(Eucalyptus camaldulensis)
0-15 23.45 22.27 23.46 21.76 -7.21
16-30 24.37 23.36 22.98 22.03 -9.60
30-60 19.54 18.45 17.22 16.95 -13.25
60-90 18.54 17.21 17.21 16.84 -9.17
90-120 20.81 21.87 21.03 22.58 8.51
120-150 21.89 22.64 21.47 23.89 9.14
100
4.1.4.3 Sodium adsorption ratio
Data regarding sodium adsorption ratio (SAR) of soil under soil profile (0-150
cm) in open field, Acacia-based and Eucalyptus-based alley cropping systems is shown in
Fig. 5 and described in tables 4.20 to 4.22. In all the systems, pre-experimentation analysis of
SAR showed variation at different depths (0-15, 15-30, 30-60, 60-90, 90-120 and 120-150
cm).
In open field system, pre-experimentation soil SAR in control plots (no
amendment) was 54.8 (0-15 cm) which increased to 58.28 with cultivation of wheat for two
successive years(Table 4.20). At the depth of 15-30 cm, soil SAR was 46.17 which increased
to 51.78 with cultivation of wheat. Soil SAR also showed variation with application of
amendments and the highest reduction was observed in upper layers (0-15 cm and 15-30 cm
respectively) in treatment plots applied with N 60 kg + FYM-20 Mg ha-1. Variation in soil
SAR in deep layers up to 150 cm as affected with application of different amendments
showed that SAR increased in deeper layer of soil profile to varying magnitude.
In Acacia-based systems, soil SAR in respective control treatment (no
amendment) at the start of experimentation was 48.52 (0-15 cm) which decreased to 41.35
with cultivation of wheat for two years(Table 4.21). At the depth of 15-30 cm, soil SAR was
54.75 which decreased to 48.63 with cultivation of wheat. Soil SAR also showed variation
with application of amendments and the highest reduction was observed in upper layers (0-
15, 15-30 cm respectively) in treatment plots applied with treatment (N 60 kg + FYM-20
Mg ha-1 ). In case of sole plantation, reduction in pH was observed in upper 0-15 and 15-30
cm, respectively. Variation in soil SAR in deep layers up to 150 cm as affected with
application of different amendments showed that SAR decreased in upper layers to varying
levels. In case of sole plantation, reduction in SAR was observed in upper 0-15 and 15-30
cm, respectively.
In Eucalyptus based systems, soil SAR (Table 4.22) in respective control
treatment (no amendment) at the start of experimentation was 48.52 (0-15 cm) which
decreased to 41.35 with cultivation of wheat for two years. At the depth of 15-30 cm, soil
SAR was 54.75 which decreased to 48.63 with cultivation of wheat. Soil SAR also showed
101
variation with application of amendments and the highest reduction was observed in upper
layers (0-15, 15-30 cm respectively) in plots applied with treatment (N 60 kg + FYM-20 Mg
ha-1 ). Variation in SAR in deep layers up to 150 cm as affected with application of different
amendments are showed that SAR decreased in upper layers to varying levels. In case of sole
plantation, minor reduction in SAR was observed in upper 0-15 and 15-30 cm, respectively.
102
Figure 5. Effect of different soil amendments on soil sodium adsorption ratio (SAR)
under open field, Acacia- and Eucalyptus-based alley cropping systems
-20
-10
0
10
20
T0 T1 T2 T3 T4 T5
0 to 15 cm
-20
-10
0
10
20
T0 T1 T2 T3 T4 T5
60 to 90 cm
-20
-10
0
10
20
T0 T1 T2 T3 T4 T5
16 to 30 cm
0
10
20
30
T0 T1 T2 T3 T4 T5
90 to 120 cm
-20
0
20
T0 T1 T2 T3 T4 T5
30 to 60 cm
Open crop field Acacia based alley
Eucalyptus-based alley
0
20
40
T0 T1 T2 T3 T4 T5
120 to 150 cm
Open crop field Acacia based alley
Eucalyptus-based alley
103
Table 4.20 Effect of amendments on soil sodium adsorption ratio (SAR) in open field
conditions.
Treatment Depth
(cm)
Open crop field
Nov
2011
May
2012
Nov
2012
May
2013
% change
over initial
value
Control (To)
0-15 54.81 54.76 47.17 58.28 6.33
16-30 46.17 63.28 47.57 51.78 12.15
30-60 43.28 56.57 46.27 48.22 11.41
60-90 41.25 42.87 40.51 44.27 7.32
90-120 47.42 63.57 55.67 55.56 17.17
120-150 41.65 45.26 43.87 48.29 15.94
N 60 kg ha-1
(T1)
0-15 44.57 63.62 34.35 49.84 11.82
16-30 55.14 57.17 51.82 61.76 12.01
30-60 53.27 56.42 57.23 58.37 9.57
60-90 54.27 59.49 57.23 60.29 11.09
90-120 44.37 49.27 46.57 51.39 15.82
120-150 46.16 51.37 49.27 53.13 15.10
N 120 kg ha-1
(T2)
0-15 46.83 49.37 42.89 52.76 12.66
16-30 48.46 51.13 54.84 55.53 14.59
30-60 48.29 53.78 45.28 55.37 14.66
60-90 52.17 56.24 54.03 57.82 10.83
90-120 44.26 49.26 47.19 51.17 15.61
120-150 45.15 47.34 46.27 49.23 9.04
FYM 20
Mg ha-1 (T3)
0-15 57.65 52.75 54.36 50.12 -13.06
16-30 49.72 47.51 48.77 43.45 -12.61
30-60 41.24 43.96 42.82 45.1 9.36
60-90 49.67 54.23 52.37 56.25 13.25
90-120 44.27 48.97 46.21 50.26 13.53
120-150 44.53 59.72 50.76 54.38 22.12
N 60 kg +
FYM 20 Mg
ha-1 (T4)
0-15 59.21 48.62 54.15 49.86 -15.79
16-30 49.95 47.21 44.43 41.81 -16.30
30-60 44.37 43.28 45.26 39.51 -10.95
60-90 36.65 40.26 39.07 42.15 15.01
90-120 38.24 41.12 40.14 43.15 12.84
120-150 34.27 38.04 36.21 40.26 17.48
104
Table 4.21 Effect of amendments on soil sodium adsorption ratio (SAR) Acacia-based
agroforestry systems.
Treatment Depth
(cm)
Acacia-based agroforestry systems
Nov
2011
May
2012
Nov
2012
May
2013
% change
over initial
value
Control (To)
0-15 48.52 52.63 54.44 41.35 -14.78
16-30 54.75 47.86 51.55 48.63 -11.18
30-60 51.36 48.29 50.37 46.07 -10.30
60-90 49.16 54.12 53.26 56.46 14.85
90-120 46.58 52.04 48.37 54.25 16.47
120-150 45.25 49.37 46.27 53.26 17.70
N 60 kg ha-1 (T1)
0-15 54.32 47.53 52.24 47.35 -12.83
16-30 57.62 54.3 61.74 48.65 -15.57
30-60 53.28 49.17 54.35 48.27 -9.40
60-90 44.55 47.59 45.97 49.24 10.53
90-120 41.29 45.35 43.15 47.21 14.34
120-150 39.26 42.95 41.29 43.71 11.33
N 120 kg ha-1 (T2)
0-15 46.22 45.93 43.34 39.15 -15.30
16-30 53.32 52.53 49.14 47.84 -10.28
30-60 51.23 48.56 47.36 42.37 -17.29
60-90 42.06 45.87 43.69 47.26 12.36
90-120 39.27 42.26 41.29 44.65 13.70
120-150 42.95 47.55 45.23 49.26 14.69
FYM 20 Mg ha-1
(T3)
0-15 53.02 50.63 47.64 43.64 -17.69
16-30 55.72 50.83 43.64 46.54 -16.48
30-60 51.34 55.37 47.29 43.24 -15.78
60-90 41.33 44.37 42.97 45.28 9.56
90-120 44.28 47.56 45.29 49.57 11.95
120-150 48.51 52.66 51.72 54.71 12.78
N 60 kg +FYM
20 Mg ha-1 (T4)
0-15 67.52 61.33 62.34 55.44 -17.89
16-30 56.32 55.53 49.34 46.54 -17.37
30-60 55.87 54.14 50.97 45.67 -18.26
60-90 43.19 48.55 46.28 50.43 16.76
90-120 41.29 47.33 44.29 49.36 19.54
120-150 45.29 52.97 49.47 55.36 22.23
Pure Tree Plantation (Acacia nilotica)
0-15 60.32 49.83 56.04 55.44 -8.09
16-30 63.22 62.43 54.04 57.44 -9.14
30-60 60.26 58.23 57.37 55.37 -8.11
60-90 59.13 57.16 55.12 52.34 -11.48
90-120 53.07 58.63 56.23 60.57 14.13
120-150 51.37 54.29 52.56 57.56 12.05
105
Table 4.22 Effect of amendments on soil sodium adsorption ratio (SAR) Eucalyptus-
based agroforestry systems.
Treatment Depth
(cm)
Eucalyptus-based agroforestry systems
Nov
2011
May
2012
Nov
2012
May
2013
% change
over initial
value
Control (To)
0-15 53.45 51.42 52.61 49.75 -6.92
16-30 57.31 40.82 48.67 54.85 -4.29
30-60 57.26 53.51 52.44 53.84 -5.97
60-90 48.82 54.82 51.82 55.37 13.42
90-120 49.23 57.39 54.12 58.26 18.34
120-150 41.29 45.29 43.59 47.56 15.19
N 60 kg ha-1 (T1)
0-15 49.76 46.77 45.61 46.35 -6.85
16-30 53.45 51.28 42.33 46.86 -12.33
30-60 55.28 53.85 49.27 47.55 -13.98
60-90 51.38 57.43 53.29 59.16 15.14
90-120 50.28 56.29 53.97 54.33 8.05
120-150 49.65 54.31 51.37 56.87 14.54
N 120 kg ha-1 (T2)
0-15 51.71 42.79 47.61 46.56 -9.96
16-30 61.48 46.53 55.07 52.76 -14.18
30-60 57.26 61.27 58.77 63.33 10.60
60-90 54.88 59.34 56.19 59.60 8.60
90-120 47.22 55.43 49.34 57.36 21.47
120-150 49.55 53.67 51.33 55.10 11.20
FYM 20 Mg ha-1
(T3)
0-15 64.11 60.27 58.23 56.31 -12.17
16-30 64.25 61.46 58.46 56.12 -12.65
30-60 61.27 59.37 55.71 51.44 -16.04
60-90 53.57 57.65 56.44 59.76 11.55
90-120 50.29 54.89 51.27 55.36 10.08
120-150 45.14 50.14 48.37 53.45 18.41
N 60 kg +FYM 20
Mg ha-1 (T4)
0-15 58.52 49.51 47.19 49.85 -14.82
16-30 55.76 41.79 46.55 48.26 -13.45
30-60 58.34 56.74 53.67 51.54 -11.66
60-90 46.22 50.67 48.36 52.37 13.31
90-120 44.51 47.02 45.97 48.24 8.38
120-150 46.37 49.28 48.21 50.26 8.39
Pure Tree
Plantation
(Eucalyptus
camaldulensis)
0-15 52.36 47.26 45.69 51.07 -2.46
16-30 64.37 59.36 57.98 61.89 -3.85
30-60 61.27 57.29 57.37 54.64 -10.82
60-90 58.36 57.76 54.27 53.26 -8.74
90-120 50.67 53.03 52.67 54.57 7.70
120-150 43.07 46.56 43.26 47.34 9.91
106
4.1.5 Discussion
The results described in the preceding section are discussed in the light of literature
collected for comparison and clarifications.
4.2.5.1 Wheat growth and production under sole cropping and alley cropping systems
Results of our studies presented in Tables 4.1 to 4.10 showed that yield and yield
components of wheat grown in sole cropping and in agroforestry systems (Acacia and
Eucalyptus based) were affected with application of nitrogen fertilizer and farm yard manure
(applied solely or jointly with different formulations). Minimum level of recorded parameters
was observed in control (no amendment); whereas maximum level was achieved in treatment
plots applied with higher level of fertilizers (FYM-20 Mg ha-1 +N 60 kg ha-1).
In general, wheat yield and yield components responded positively to organic and
inorganic N-treatments. Combined dose of farm yard manure and nitrogen produced
comparatively higher yield components than control and other treatments. The carry-over
effects of N for optimum crop growth from the previous year could possibly explain the
improved yield components in fertilized plots as stated by Singh et al. (2004). The greater
nitrogen availability (Anatoliy and Thelen, 2007) and organic carbon in the form of farm
yard manure (Blair et al., 2006; Sullivan et al., 2007) in nitrogen fertilizer and/or organic
matter applied plots might be the other reasons for improved yield components as compared
to unfertilized plots.
In sole cropping, plant density increased gradually with the enhancement of fertility
status with application of fertilizer/soil amendments (Table 4.1). The increased accessibility
of nutrient (Ortega et al., 2002; Blair et al., 2006), improvement of soil water holding
capacity and reduction of volatilization of nitrogenous fertilizer observed in plots
incorporated with FYM integrated with N might be the possible reasons for improved
germination leading to higher crop stand. It may also be due to softness of soil caused by
application of manure which facilitated roots expansion rapidly due to higher water holding
capacity. Results in Table 4.2 revealed that fertilized plots had higher plant height than
control treatment where no amendment was applied. The tallness in fertilized plots (nitrogen
107
and/or farm yard manure) might be associated with instant availability of nitrogen from
applied fertilizer (Sainju et al., 2007). Optimum amount of soil water and organic carbon
from farm yard manure (Dolan et al., 2006) resulted in increased cell division, expansion and
enlargement and ultimately production of taller plants.
Leaf area of a plant is product of higher assimilation rate of photosynthesized product
(Lopez-Bellido et al., 1998), and is affected by light use efficiency (Halvorson et al., 2001b;
Malhi et al., 2006). As shown in Table 4.3, mixing FYM with nitrogen resulted in greater
average leaf area as compared to either sole application of FYM or control plots (no
amendment). Higher number of tillers m-2, grains per spike and 1000-grains weight as shown
in Table 4.3 to 4.6 showed that fertilized plots had positive signs as compared to control.
The higher number of spike m-2
might be attributed to the adequate nitrogen availability,
which had facilitated the tillering ability of the wheat crop (Jan and Khan, 2002). Similarly,
results showed that application of fertilizer and/or farm yard manure improved the tillering
potential. Badaruddin et al. (1999) and Hossain et al. (2002) have also reported significant
increase in tillers m-2 in experimental plots applied with organic and inorganic fertilizers.
Ayoub et al. (1994) also stated that higher spike m-2
were obtained at increased fertilizer
levels. Increased 1000-grains weight in fertilized plots might be attributed with
photosynthates accumulation or due to higher availability of nitrogen at grain formation
stage. Results of present study are in line with the findings of Khan (2009) who obtained
heavier grains in nitrogen-fertilized wheat plots as compared to unfertilized plots.
Improvement in grain, straw, biological yield and harvest index was observed in plots
amended with organic and inorganic nitrogen as compared to control (Tables 4.7 to 4.10).
The higher biological yield in fertilized plots over control would be due to higher available
nutrient in fertilized plots and comparable yield by combined applications of FYM +
Nitrogen effect seems consistant as described by Hossain et al. (2002).
108
In Acacia and Eucalyptus-based alley cropping systems, plant density, grain per
spike, 1000-grains weight and biological yield of wheat crop responded in same pattern as
observed in sole cropping (open field) system on application of different levels of
fertilizer/soil amendment. The lowest biomass was recoded in both the alley cropping
systems in their respective control (no amendment), whereas the highest biomass was
obtained in treatment plots applied with nitrogen blended with farm yard manure. Similar
results were observed by Matsi et al. (2003) and Sainju et al. (2006 ) who reported that plant
yield parameters of understorey crops in agroforestry systems improved with application of
fertilizers and farm yard manure due to higher germination status.
Wheat crop yield and yield traits were adversely affected due to shade caused by trees
(A. nilotica and E. camadulensis) in both the systems. These results are also validated to the
findings of Chaudhry (2003) who reported that plant density, plant height, number of tillers
per plant, number of grains per spike and biological yield of wheat grown in agroforestry
system reduced up to considerable extent as compared to open field system. These results are
also in conformity to the findings that yield and yield components were negatively affected
due to tree shade effect (Singh et al., 1988; Sharma, 1996).
In agroforestry systems, reduction in yield and yield components of understorey crops
may be due to competition among component crops for various resources i.e., moisture,
space, nutrients and light particularly at the formation of grain, which reduces supply of
assimilates to the developing grains. In general, trees compete with understorey crops for
various resources and thus result in high reduction in crop yield depending upon tree density,
age and level of shade. Thus, tree-crop interactions affect structure and function of agro-
ecosystems depending upon the composition of the systems (Garcia-Barrios and Ong, 2004).
109
4.1.5.2 Tree growth and wood production under sole plantation and tree based systems
Mean annual increment (MAI) of both the tree species (Acacia nilotica, Eucalyptus
camaldulensis) grown in sole plantation and in agroforestry systems was monitored for two
consective years. Results of present studies (Table 4.11 to 4.12) showed that growth rate of
A. nilotica and E. camaldulensis grown in agroforestry systems (Acacia-based and
Eucalyptus-based) was significantly higher in experimental plots applied with fertilizer and
farm yard manure (applied solely or jointly). The lowest level of mean annual increment was
observed in control plots (no amendment), whereas the highest level of mean annual
increment was observed in plots applied with fertilizer N 60 kg + FYM-20 Mg ha-1.
Better growth of trees observed in agroforestry systems may be attributed to the
application of fertilizer in the experimental plots. Thus, the trees seem to have benefitted by
exploiting fertilizer and farm yard manure amendments otherwise meant for understorey
crops. Use of fertilizers and ameliorative effect of farm yard manure in agroforestry systems
provided suitable soil environment for optimum soil microbial activity, which, in turn, might
have caused rapid mineralization of organic matter thus facilitating the uptake of nutrients by
trees. Beneficial effects of growing crops in tree plantations have also been reported by
Sharma and Singh (1992).
Results of the present study confirm findings of Szott and Kass (1993) who reviewed
the research work on application of fertilizer in various agroforestry systems including alley
cropping and reported that fertilizer response was positive in alley cropping systems. Ahmed
(1991) has also reported that growth of A. nilotica and E. camaldulensis improved in saline
environment when these plants were applied with soil amendments.
Our results agreed with the findings of Gupta (1991) and Datta and Singh (2007)
regarding the enhanced yield component of wood production on degraded land. It was due to
better soil conditions having reclamation activities and the soil regeneration potential of trees
on degraded land. Dhyani and Tripathi (1999) also found that intercropping had positive
effects on tree growth parameter as compared to sole tree plantations due to fertilizer
application, land management operations and improved tree-crop management.
110
4.1.5.3 Biomass productivity under different systems
The biomass productivity status in any ecosystem is governed by prevailing climatic
conditions and edaphic characteristics. The increased availability of nutrients in the soil due
to application of nitrogen fertilizer and/or farm yard manure might be the possible reason for
increased biomass production in agroforestry systems. Moreover, in case of compatible
agroforestry systems, total productivity of the systems is increased due to several reasons like
higher resistance to recurrent ecological alterations, increased availability of vital nutrients
and healthy effect of root exudates in rhizospheres, enhanced consumption and reutilization
of resources as stated by Liebman and Gallandt (1997).
In intercropping systems, yield of component of intercrop may be reduced but total
yield of intercrops can be significantly greater than that of each crop in a monoculture if
proper system of intercropping is used. In present studies, biomass production gradually
increased in alley cropping systems by the application of suitable amendments. There was
more compatibility in Acacia-wheat based system as compared to Eucalyptus-wheat based
system as the former supported higher growth of understorey wheat crop. Fertilization
supplemented farm yard manure treatment (N 60 kg + FYM-20 Mg ha-1 ) supported higher
biomass production of wheat in all the systems (open field, Acacia and Eucalyptus based
systems). Our results are in agreement with the findings of the previous researchers like
Dhyani and Tripathi (1999), Bhatt et al. (2005) and Datta and Singh (2007).
111
4.1.5.4 Soil properties variation in different cropping systems with application of
amendments
4.1.5.4.1 pH
In open field conditions, soil pH increased with in upper soil layer (0-15 cm) with
growing of wheat crop for two years in control treatment (no amendment). This increase may
be attributed to the continuous application of brackish irrigations water (SAR 40.2 and RSC
21.2 Mmolc L-1) to wheat crop during both the cropping seasons. However, application of
farm yard manure alone or blended with nitrogen fertilizer resulted in reduction of soil pH in
soil profile at various depths (Table 4.14 to 4.16). The decrease in pH may be outcome of
application of farm yard manure which had ameliorative effect on soil pH during both the
cropping seasons.
In tree based (Acacia and Eucalyptus) alley cropping systems, tree plantation
improved soil pH at varying levels in control as well as with application of amendments. In
present studies, more pH reduction was observed in Acacia-based systems as compared to
Eucalyptus-based cropping system. Similar trend was followed in their sole plantations as A.
nilotica plantation was found to have more restorative and ameliorative effect as compared to
E. camaldulensis. Possible reason for higher ameliorative effect may be due to higher leaf
litter fall in A. nilotica as compared to E. camaldulensis and plasticity effect i.e., slower
decomposition rate, of leaves of E. camaldulensis. Application of organic amendment (farm
yard manure especially blended with nitrogen) has enhanced ameliorative effect on soil pH at
various depths in soil profile.
The primary factor responsible for reduction of soil pH may be reduced
evapotranspiraion, better water holding capacity of soil, fall of leaf litter and higher microbial
activities in improved microclimate prevailing in alley cropping systems as compared to open
field conditions. Higher plant biodiversity in the alley cropping systems leads to higher
respiration of CO2 (Robbins, 1986) which reacts with water to make H2CO3 which upon
dissociation releases H+. The proton thus released is primary force responsible for reduction
in soil pH (Qadir et al., 2005). Litter component of tree is a measure of the net H+ release and
hence reduction in soil pH. Our results are in conformity with the findings of Singh et al.,
1995 and Basavaraja et al., 2011.
112
4.1.5.4.2 Soil electrical conductivity
Electrical conductivity (EC) is a measure of soluble salts present in soil-water system.
Results of our studies (Table 4.17 to 4.19) conducted in open field condition showed that soil
EC increased in upper soil layer (0-15 cm) with growing of wheat crop for successive two
years in control (no amendment) condition. The increase may be attributed to continuous use
of brackish water for irrigation of the wheat crop during both the cropping seasons.
However, application of farm yard manure in blended form with nitrogen fertilizer resulted in
reduction of soil EC in soil profile. The decrease in soil EC may be outcome of application of
farm yard manure which had ameliorative effect during both cropping seasons.
In Acacia-based and Eucalyptus-based alley cropping systems, soil electrical
conductivity decreased at varying level in control plots as well as in plots applied with
amendments. In present studies, more soil electrical conductivity reduction was observed in
Acacia based systems as compared to Eucalyptus based ones. Similar trend was followed in
their sole plantations as A. nilotica plantation was found to be more restorative and
ameliorative as compared to E. camaldulensis. Overall, the leaching of soluble salts from the
root zone to the lower soil depths with irrigation and/or rainwater remained the main cause
for decreasing electrical conductivity of soil. Leaching of salts is facilitated by the roots of
trees/vegetation by providing channels for water and solute movement to the lower soil
profile (Qadir et al., 2003).
Application of farm yard manure alone or blended with nitrogen has enhanced
ameliorative effect on soil EC at various depths in soil profile. Addition of organic matter by
tree plantation is reported to increase porosity of soil (Grag, 1998). In tree farming systems,
roots in soil profile decay oftenly and this phenomenon leads to conversion of soil pores into
macropores (Yunusa et al., 2002; Devine et al., 2002), which increases infilteration rate and
facilitates leaching of salts. Addition of organic amendments improves soil structure and
increases porosity. Such positive development in alley cropping systems leads to enhanced
reduction in soil EC.
113
4.1.5.4.3 Soil sodium adsorption ratio
Soduim adsorption ratio (SAR) is the measure of sodicity present in soil-water
system. Results of our studies conducted in open field condition showed that soil SAR
increased in upper soil layer (depth 0-15 cm) after growing of wheat crop for successive two
years in control (no amendment) condition (table 4.20 to 4.22). The increase may be
attributed to continuous irrigations with high SAR and RSC (brackish) water used for
irrigation of the wheat crop during both cropping seasons. However, application of farm yard
manure in blended form with nitrogen fertilizer resulted in reduction of soil SAR in the
profile. The decrease in soil SAR with farm yard manure appears most probably through
Ca2+ released from soil lime as a result of CO2 released during FYM biochemical oxidation.
In Acacia and Eucalyptus-based alley cropping systems, soil SAR decreased at
varying levels in control treatment as well as in treatments where application of amendments
were made. In present studies, more soil SAR reduction was observed in Acacia-based
systems as compared to Eucalyptus-based ones. Similar trend was observed in their sole
plantations as A. nilotica plantation was found to be more restorative and ameliorative as
compared to E. camaldulensis. Overall, leaching of soluble salts from root zone to the lower
soil depths with irrigation and/or rainwater remained the main cause for decreasing electrical
conductivity of soil. Leaching of salts is facilitated by the roots of trees/vegetation by
providing channels for water and solute movement to lower soil profile (Qadir et al., 2003).
Application of farm yard manure alone or blended with nitrogen has enhanced
ameliorative effect on soil SAR at various depths in the soil profile. Addition of organic
matter by tree plantation is reported to increase porosity of soil (Grag, 1998). Addition of
organic amendments improved soil structure and increased the soil porosity. Such positive
signs in alley cropping systems lead to enhanced reduction in soil SAR.
114
4.2 Study 2: Interactive effect of varying levels of gypsum and farm yard manure on
biomass production of para grass in open field, Acacia and Eucalyptus based
alley cropping systems with different light intensity regimes
4.2.1 Grass growth and production
4.2.1.1 Stolon height
The results of stolon height (cm) of para grass (Table 4.23) showed significant
interactive effect of varying levels of gypsum and farm manure on stolon height (cm) of para
grass in open field, Acacia-based and Eucalyptus-based alley cropping systems with different
light intensity regimes. These results indicated that stolon height of para grass grown in
experimental plots increased with increase in fertility status in all the systems (open and
agroforestry systems).
In open field conditions, stolon height was 41.6 cm in control plots (no amendment)
whereas it was 64.8 cm (55.8% higher) in plots applied with amendments (Gypsum @ GR
100% + FYM 10 Mg ha-1) during 1st year of experimentation (2011-12). During 2nd year
(2012-13), stolon height was 43.9 cm in control plots whereas it was 68.2 cm (55.4% higher)
in plots applied with treatment (Gypsum @ GR 100% + FYM 10 Mg ha-1). Combined data
for both the years showed that average stolon height increased from 41.6 (control) to 64.8 cm
(55.8% higher) (Gypsum @ GR 100% + FYM 10 Mg ha-1).
In Acacia-based agroforestry system, stolon height was 29.3 cm in control plots (no
amendment) whereas it was 61.5 cm (110% higher) in plots applied with (Gypsum @ GR
100% + FYM 10 Mg ha-1) during 1st year of experimentation (2011-12). In 2nd year (2012-
13), stolon height of 33.6 cm was recorded in control treatment whereas it was 51.5 cm
(53.3% higher) in plots applied with treatment (Gypsum @ GR 100% + FYM 10 Mg ha-1).
Combined data for both the years showed that stolon height increased from 31.4 (control) to
48.2 cm (53.5% higher) in treatment where the treatment (Gypsum @ GR 100% + FYM 10
Mg ha-1) was applied.
115
In Eucalyptus-based agroforestry system, stolon height was 26.8 cm in control plots
(no amendment) whereas it was 37.3 cm (39.2% higher) in plots applied with treatment
(Gypsum @ GR 100% + FYM 10 Mg ha-1) during 1st year of experimentation (2011-12).
During 2nd year (2012-13), stolon height was 28.6 cm in control treatment plots while it was
41.3 cm (44.4% higher) in plots where Gypsum @ GR 100% + FYM 10 Mg ha-1 was
applied. Combined data for both the years showed that stolon height increased from 27.7 cm
(control) to 39.3 cm (41.9% higher) (Gypsum @GR 100% + FYM 10 Mg ha-1).
Overall comparison of light factor in all the systems under observation (open field,
Acacia-based and Eucalyptus-based systems) showed that stolon height was significantly
affected in all the systems. Stolon height exhibited a decreasing trend from open field to
Acacia-based and Eucalyptus-based agroforestry system.
Comparison of soil fertility in all three systems under study i.e., open field, Acacia-
based and Eucalyptus-based systems, revealed that stolon height increased with application
of soil amendments in all the systems. A progressive increase in stolon height was recorded
from control plots (no amendment) to different levels of amendments with the highest plant
height in plots applied with treatment (Gypsum @ GR 100% + FYM 10 Mg ha-1).
116
Table 4.23: Effect of fertilizer application on stolon height (cm) of para gras grown in open field, Acacia and Eucalyptus-based
agroforestry systems.
Treatments Open field
(PAR 100%)
Acacia-based agroforestry
system (PAR 76±3%)
Eucalyptus-based agroforestry
system (PAR 66±3%)
Grand
Mean
Year-1 Year-II Mean Year-I Year-II Mean Year-I Year-II Mean
Control (To)
39.3±0.88 43.9±0.68 41.6c 29.3±0.87 33.5±2.08 31.4c 26.8±0.52 28.6±0.80 27.7c 33.6d
Gypsum @ GR
100% (T1)
42.3±1.48 46.3±1.74 44.3c 32.7±1.34 36.6±1.50 34.7bc 27.6±1.68 31.2±1.82 29.4bc 36.1cd
FYM 20 Mg
ha-1 (T2)
50.6±1.91 54.3±2.86 52.4b 35.1±1.26 39.9±1.18 37.5c 32.2±1.45 35.3±1.48 33.6b 41.2c
Gypsum @ GR
50%+FYM 10
Mg ha-1 (T3)
52.3±2.13 60.1±1.83 56.2b 41.0±1.35 46.3±1.31 43.7b 35.1±1.30 39.8±1.74 37.4ab 45.7b
Gypsum @ GR
100%+FYM 10
Mg ha-1 (T4)
61.5±1.6 68.2±1.06 64.8a 44.8±2.07 51.4±2.17 48.2a 37.3±2.12 41.3±2.61 39.3a 50.7a
Mean 51.8A 39.1B 33.5C
Means values followed by different letter(s) in each category are statistically different using least significantly difference (LSD) test at 5% level
of probability.
117
4.2.1.2 Culm length
The results of culm length (m) of para grass (Table 4.24) showed significant
interactive effects of varying levels of gypsum and farm manure on culm length of para grass
in open field, Acacia-based and Eucalyptus-based alley cropping systems with different light
intensity regimes. These results illustrated that culm length of para grass grown in
experimental plots increased with increase in fertility status in all the systems (open and
agroforestry systems).
In open field conditions, culm length was 2.57 m in control plots (no amendment)
whereas it was 3.59 m (39.7% higher) in plots applied with treatment (Gypsum @ GR 100%
+ FYM 10 Mg ha-1) treatment during 1st year of experimentation (2011-12). In 2nd year
(2012-13), culm length was recorded as 2.73 m in control plots whereas it was 3.83 m
(40.3% higher) in plots applied with treatment (Gypsum @ GR 100% + FYM 10 Mg ha-1).
Combined data for both the years showed that culm length increased from 2.65 m (control) to
3.71 m (40% higher) (Gypsum @ GR 100% + FYM 10 Mg ha-1).
In Acacia-based agroforestry system, culm length was recorded as 1.89 m in control
(no amendment) whereas it was 3.10 m (64% higher) in plots applied with treatment
(Gypsum @ GR 100% + FYM 10 Mg ha-1) during 1st year of study (2011-12). During 2nd
year (2012-13), culm length was 2.06 m in control plots whereas it was 3.47 m (68.4%
higher) in plots applied with treatment (Gypsum @ GR 100% + FYM 10 Mg ha-1).
Combined data for both the years showed an increase in culm length from 1.98 m (control) to
3.29 m (66.2% higher) (Gypsum @ GR 100% + FYM 10 Mg ha-1).
In Eucalyptus-based agroforestry system, culm length was 1.69 m in control plots (no
amendment) whereas it was 2.93 m (73.4% higher) in plots applied with treatment (Gypsum
GR 100% + FYM 10 Mg ha-1) during 1st year of experimentation (2011-12). For 2nd year
(2012-13), culm length was 1.81 m in control plots whereas it was 3.04 m (68% higher) in
plots applied with treatment (Gypsum@ GR 100% + FYM 10 Mg ha-1). Combined data for
both the years showed that culm length increased from 1.75 m (control) to 2.99 m (70.9%
higher) (Gypsum @ GR 100% + FYM 10 Mg ha-1).
118
Overall comparison of light factor in all the systems under study (open field, Acacia-
based and Eucalyptus-based systems), showed that culm length was significantly affected in
all the systems. Culm length exhibited decreasing trend from open field (3.21 m) to Acacia-
based (2.82 m) and Eucalyptus-based (2.44 m) agroforestry system.
Comparison of soil fertility in all three systems under study i.e., open field, Acacia–
based and Eucalyptus-based systems, revealed that plant culm length increased with
application of soil amendments in all the systems. A progressive gain in culm length was
observed in control plots (no amendment) from 2.12 m to various levels of amendments and
the highest culm length (2.99 m) in plots applied with treatment (Gypsum @ GR 100% +
FYM 10 Mg ha-1).
119
Table 4.24: Effect of fertilizer application on culm length (m) of para grass grown in open field and agroforestry systems.
Treatments
Open field
(PAR 100%)
Acacia-based agroforestry
system (PAR 76±3%)
Eucalyptus-based agroforestry
system (PAR 66±3%)
Grand
Mean
Year-1 Year-II Mean Year-I Year-II Mean Year-I Year-II Mean
Control (To)
2.57±0.76 2.73±0.69 2.65c 1.89±0.59 2.06±0.86 1.98c 1.69±0.84 1.81±0.49 1.75d 2.12c
Gypsum @ GR
100% (T1)
2.93±0.89 3.05±0.65 2.99c 2.58±0.48 2.93±0.76 2.76b 2.26±0.72 2.39±0.35 2.33c 2.69b
FYM 20 Mg
ha-1 (T2)
3.37±0.92 3.55±0.93 3.46b 3.08±0.94 3.29±0.32 3.19a 2.61±0.34 2.77±0.19 2.69b 3.11a
Gypsum @ GR
50%+FYM 10
Mg ha-1 (T3)
3.18±0.66 3.31±0.55 3.25b 2.78±0.79 3.02±0.26 2.90ab 2.56±0.82 2.53±0.31 2.55b 2.89b
Gypsum @ GR
100%+FYM 10
Mg ha-1 (T4)
3.59±0.69 3.83±0.87 3.71a 3.10±0.54 3.47±0.85 3.29a 2.93±0.28 3.04±0.36 2.99a 3.33a
Mean 3.21A 2.82B 2.44C
Means values followed by different letter(s) in each category are statistically different using least significantly difference (LSD) test at 5% level of probability.
120
4.2.1.3 Number of tillers per plant
The results for number of tillers per plant of para grass (Table 4.25) showed
significant interactive effect of various levels of gypsum and farm yard manure on number of
tillers per plant of para grass in open field, Acacia-based and Eucalyptus-based alley
cropping (agroforestry) systems with different regimes of light intensity. These results
depicted that number of tillers per plant of para grass grown in each treatment of
experimental plot increased with increase in fertility status in systems under study (open and
agroforestry systems).
In open field conditions, number of tillers was 17 per plant in control plots (no
amendment) whereas it was 33 m-2 (94.1% higher) in plots applied with treatment (Gypsum
GR @ 100% + FYM 10 Mg ha-1) in 1st year of experimentation (2011-12). During 2nd year
(2012-13), number of tillers was 19 in control plots whereas it was 36 (89.5% higher) in plots
having treatment (Gypsum @ GR 100% + FYM 10 Mg ha-1). Combined data for both the
years showed that number of tillers increased from 18 (control) to 34 (88.9% higher) in plots
applied with Gypsum GR 100% + FYM 10 Mg ha-1.
In Acacia-based agroforestry system, number of tillers was 13 per plant in control
plots (no amendment) whereas it was 23 m-2 (76.9% higher) in plots applied with treatment
(Gypsum @ GR 100% + FYM 10 Mg ha-1) in 1st year of experimentation (2011-12). During
2nd year (2012-13), number of tillers was 16 in control treatment plots whereas it was 27
(68.8% higher) in plots having treatment (Gypsum @ GR 100% + FYM 10 Mg ha-1).
Combined data for both the years showed that number of tillers increased from 14 (control)
to 25 (78.6% higher) in plots applied with Gypsum @GR 100% + FYM 10 Mg ha-1.
In Eucalyptus-based agroforestry system, number of tillers was 9 per plant in control
plots (no amendment) whereas it was 18 m-2 (two times higher) in plots applied with
treatment (Gypsum @ GR 100% + FYM 10 Mg ha-1) in 1st year of experimentation (2011-
12). During 2nd year (2012-13), number of tillers was 11 in control treatment plots whereas it
was 20 (81.8% higher) in plots having treatment (Gypsum @ GR 100% + FYM 10 Mg ha-1).
Combined data for both the years showed that number of tillers increased from 10 (control)
to 19 (90% higher) in plots treated with Gypsum @ GR 100% + FYM 10 Mg ha-1.
121
Over all comparison of light factor in all the systems under observation (open field,
Acacia-based and Eucalyptus-based systems), showed that number of tillers per plant was
significantly affected in all the systems. Number of tillers exhibited a decreasing trend from
open field (27 numbers) to Acacia-based (20 numbers) and Eucalyptus-based (14 numbers)
agroforestry system.
Comparison of soil fertility in all three systems under study i.e., open field, Acacia
and Eucalyptus-based systems, revealed that number of tillers per plant increased with
application of soil amendments in all the systems. A progressive increase in number of tillers
per plant was recorded from control plots (14 numbers) to different levels of amendments
with the highest number of tillers per plant (26 numbers) in plots applied with treatment
(Gypsum @ GR 100% + FYM 10 Mg ha-1).
122
Table 4.25: Effect of fertilizer application on No. of tillers of para gras per plant grown in open field and agroforestry systems
Treatments
Open field
(PAR 100%)
Acacia-based agroforestry
system (PAR 76±3%)
Eucalyptus-based agroforestry
system (PAR 66±3%)
Grand
Mean
Year-1 Year-II Mean Year-I Year-II Mean Year-I Year-II Mean
Control (To)
17±0.85 19±0.96 18e 13±0.85 15±0.91 14d 9±1.08 11±1.11 10e 14d
Gypsum @ GR
100% (T1)
22±1.55 26±1.71 24d 17±1.38 19±0.82 18c 11±1.38 13±0.85 12d 18c
FYM 20 Mg
ha-1 (T2)
26±1.25 28±1.71 27c 19±1.25 23±1.32 21b 13±0.87 16±1.49 15c 21bc
Gypsum @ GR
50%+FYM 10
Mg ha-1 (T3)
30±1.58 33±1.19 31b 21±1.58 26±1.04 23ab 14±1.44 17±1.31 16b 24ab
Gypsum @ GR
100%+FYM 10
Mg ha-1 (T4)
33±1.44 36±1.29 34a 23±1.68 27±1.65 25a 18±1.89 20±1.65 19a 26a
Mean 27A 20B 14C
Means values followed by different letter(s) in each category are statistically different using least significantly difference (LSD) test at 5% level
of probability.
123
4.2.1.4 Fresh biomass
Data recorded for fresh weight (Mg ha-1) of para grass (Table 4.26) showed
significant interactive effect of varying levels of gypsum and farm manure on fresh weight of
para grass grown in open field, Acacia-based and Eucalyptus-based alley cropping systems
with different light intensity regimes. These results indicated that fresh weight of para grass
grown in experimental plots increased with increase in fertility status in all the systems (open
and agroforestry systems).
In open field conditions, fresh weight was 31.8 Mg ha-1 in control plots (no
amendment) whereas it was 51.7 Mg ha-1 (62.6% higher) in plots treated with (Gypsum @
GR 100% + FYM 10 Mg ha-1) were made during 1st year of the study (2011-12). During 2nd
year (2012-13), fresh weight was 33.8 Mg ha-1 in control plots whereas it was 54.7 Mg ha-1
(61.8% higher) in plots applied with treatment (Gypsum @ GR 100% + FYM 10 Mg ha-1).
Combined data for both the years showed that fresh weight increased from 32.8 Mg ha-1
(control) to 52.8 Mg ha-1 (61% higher) (Gypsum @ GR 100% + FYM 10 Mg ha-1).
In Acacia-based agroforestry system, fresh weight was recorded as 27.32 Mg ha-1 in
control plots (no amendment) whereas it was 45.15 Mg ha-1 (65.3% higher) in plots applied
with treatment (Gypsum GR @ 100% + FYM 10 Mg ha-1) during 1st year of experimentation
(2011-12). During 2nd year (2012-13), fresh weight (Mg ha-1) was 30.12 Mg ha-1 in control
plots, whereas it was 50.7 Mg ha-1 (68.3% higher) in plots applied with amendments
(Gypsum @ GR 100% + FYM 10 Mg ha-1). Combined data for both the years showed that
fresh weight (Mg ha-1) increased from 28.7 Mg ha-1 (control) to 47.9 Mg ha-1 (66.9%
higher) (Gypsum @ GR 100% + FYM 10 Mg ha-1).
In Eucalyptus-based agroforestry system, fresh weight (Mg ha-1) was 23.4 Mg ha-1 in
control plots (no amendment) and 43.1 Mg ha-1 (84.2% higher) in plots applied with
(Gypsum GR 100% + FYM 10 Mg ha-1) during 1st year of experimentation (2011-12).
During 2nd year (2012-13), fresh weight (Mg ha-1) was 25.9 Mg ha-1 in control plots and 46.2
Mg ha-1 (78.4% higher) in plots applied with treatment (Gypsum GR 100% + FYM 10 Mg
124
ha-1). Combined data for both the years showed that fresh weight increased from 24.6 Mg ha-
1 (control) to 44.7 Mg ha-1 (81.7% higher) (Gypsum @ GR 100% + FYM 10 Mg ha-1).
Over all comparison of light factor in all the systems (open field, Acacia-based and
Eucalyptus-based systems), showed that fresh weight was significantly affected in all the
systems. Data of fresh weight (Mg ha-1) presented a decreasing trend from open field to
Acacia-based and Eucalyptus-based alley cropping system.
Comparison of soil fertility in all three systems under study i.e., open field, Acacia-
based and Eucalyptus-based systems, revealed that fresh weight (Mg ha -1) increased with
application of soil amendments in all the systems. A progressive increase in fresh weight was
recorded from control (no amendment) to different levels of amendments with the highest
fresh weight (Mg ha-1) in plots applied with treatment (Gypsum @ GR 100% + FYM 10 Mg
ha-1).
125
Table 4.26: Effect of fertilizer application on fresh weight (Mg ha-1) of para gras grown in open field, Acacia and Eucalyptus-
based agroforestry systems.
Treatments
Open field
(PAR 100%)
Acacia-based agroforestry
system (PAR 76±3%)
Eucalyptus-based agroforestry
system (PAR 66±3%)
Grand
Mean
Year-1 Year-II Mean Year-I Year-II Mean Year-I Year-II Mean
Control (To)
31.8±2.09 33.8±1.25 32.8c 27.3±0.87 30.1±0.62 28.7c 23.4±0.70 25.9±0.80 24.6 c 28.7d
Gypsum @ GR
100% (T1)
37.2±1.48 40.9±1.77 38.9b 32.9±1.13 37.5±1.18 35.2bc 29.5±1.68 31.5±1.79 30.5 b 34.8cd
FYM 20 Mg
ha-1 (T2)
43.9±1.87 45.2±1.68 44.6ab 37.7±1.15 41.7±1.16 39.71b 31.8±1.34 35.6±1.57 33.7ab 39.3c
Gypsum @ GR
50%+FYM 10
Mg ha-1 (T3)
47.3±1.54 45.8±1.07 46.6ab 41.8±1.54 45.1±1.27 43.51b 37.2±1.75 40.7±1.82 38.9 ab 43.0b
Gypsum @ GR
100%+FYM 10
Mg ha-1 (T4)
51.7±2.11 54.1±1.83 52.8a 45.1±1.93 50.7±2.26 47.92a 43.1±2.11 46.2±2.61 44.7 a 49.4a
Mean 43.1A 39.0B 34.5C
Means values followed by different letter(s) in each category are statistically different using least significantly difference (LSD) test at 5% level of probability.
126
4.2.1.5 Dry biomass
The results of dry biomass (Mg ha-1) of para grass are presented in table 4.27, which
showed significant interactive effect of varying levels of gypsum and farm manure on dry
biomass of para grass grown in open field, Acacia-based and Eucalyptus-based alley
cropping systems with different light intensity regimes. These results indicated that dry
biomass of para grass grown in experimental plots increased with increase in fertility status
in all the systems (open and agroforestry systems).
In open field conditions, dry biomass of para grass was recorded as 7.69 Mg ha-1 in
control plots (no amendment; control) and 12.50 Mg ha-1 (62.5% higher) in plots applied
with treatment (Gypsum @ GR 100% + FYM 10 Mg ha-1) during first year of
experimentation (2011-12). During second year (2012-13), dry biomass was 8.18 Mg ha-1 in
control plots and it was 13.11 Mg ha-1 (60.3% higher) in plots applied with treatment
(Gypsum@ GR 100% + FYM 10 Mg ha-1). Combined data for both the years revealed that
dry biomass increased from 7.94 Mg ha-1 (control) to 12.8 Mg ha-1 (61.2% higher)
(Gypsum@ GR 100% + FYM 10 Mg ha-1).
In Acacia-based agroforestry system, dry biomass of para grass was 6.59 Mg ha-1 in
control plots (no amendment) whereas it was 10.93 Mg ha-1 (65.9% higher) in plots applied
with (Gypsum @ GR 100% + FYM 10 Mg ha-1) during 1st year of study (2011-12). During
2nd year (2012-13), dry biomass (Mg ha-1) was 7.29 Mg ha-1 in control plots whereas it was
12.28 Mg ha-1 (68.4% higher) in plots applied with treatment (Gypsum @ GR 100% + FYM
10 Mg ha-1). Combined data regarding both the years showed that dry biomass (Mg ha -1)
increased from 6.94 Mg ha-1 (control) to 11.6 Mg ha-1 (67.1% higher) (Gypsum @ GR 100%
+ FYM 10 Mg ha-1).
In Eucalyptus-based agroforestry system, dry biomass of para grass was 5.67 Mg ha-1
in control plots (no amendment) whereas it was 10.46 Mg ha-1 (84.5% higher) in plots
applied with treatment (Gypsum @ GR 100% + FYM 10 Mg ha-1) during 1st year of
experimentation (2011-12). During 2nd year (2012-13), dry biomass was 6.27 Mg ha-1 in
control plots whereas it was 11.2 Mg ha-1 (78.6% higher) in plots applied treatment (Gypsum
127
@ GR 100% + FYM 10 Mg ha-1). Combined data for both the years showed that dry biomass
increased from 5.97 Mg ha-1 (control) to 10.8 Mg ha-1 (80.9% higher) (Gypsum @ GR 100%
+ FYM 10 Mg ha-1).
Over all comparison of light factor in all the systems (open field, Acacia-based and
Eucalyptus-based systems), showed that dry biomass was significantly affected in all the
systems. Data on dry biomass showed a decreasing trend from open field to Acacia-based
and Eucalyptus-based agroforestry system.
Comparison of soil fertility in all three systems under study i.e., open field, Acacia-
based and Eucalyptus-based systems, showed that dry biomass (Mg ha-1) increased with
application of soil amendments in all the systems. A progressive increase in dry biomass was
recorded from control plots (no amendment) to different levels of amendments with the
highest fresh weight (Mg ha-1) in plots applied with treatment (Gypsum @ GR 100% + FYM
10 Mg ha-1).
128
Table 4.27: Effect of fertilizer application on dry biomass (Mg ha-1) of para gras grown in open field, Acacia-based and
Eucalyptus-based agroforestry systems
Treatments
Open field
(PAR 100%)
Acacia-based agroforestry
system (PAR 76±3%)
Eucalyptus-based agroforestry
system (PAR 66±3%)
Grand
Mean
Year-1 Year-II Mean Year-I Year-II Mean Year-I Year-II Mean
Control (To)
7.69±0.50 8.18±0.31 7.92c 6.59±0.22 7.29±0.31 6.94 c 5.67±0.22 6.27±0.52 5.97 c 6.95c
Gypsum @ GR
100% (T1)
9.05±0.37 9.91±0.40 9.44bc 7.97±0.29 9.10±0.63 8.53bc 7.15±0.41 7.63±0.47 7.39 bc 8.45b
FYM 20 Mg
ha-1 (T2)
10.6±0.44 10.9±0.41 10.8ab 9.14±0.29 10.1±0.75 9.62ab 7.72±0.32 8.63±0.36 8.17ab 9.71ab
Gypsum @ GR
50%+FYM 10
Mg ha-1 (T3)
11.4±0.37 11.1±0.28 11.3ab 10.1±0.39 10.9±0.27 10.53ab 9.02±0.33 9.85±0.73 9.43 ab 10.42ab
Gypsum @ GR
100%+FYM 10
Mg ha-1 (T4)
12.5±0.56 13.1±0.44 12.8a 10.9±0.36 12.3±0.61 11.61a 10.4±0.53 11.2±0.62 10.83 a 11.7a
Mean 10.41A 9.44B
8.36C
Means values followed by different letter(s) in each category are statistically different using least significantly difference (LSD) test at 5% level of probability.
129
4.2.2 Tree growth and wood production
4.2.2.1 Tree bole volume
The results of tree bole volume (Table 4.28) showed interactive effect of varying
levels of gypsum and farm manure on wood volume of trees in Acacia-based and Eucalyptus-
based alley cropping systems. These results indicated that tree bole volume increased by the
increase of fertility status in agroforestry systems.
In Acacia-based agroforestry system, bole volume of trees (m3 ha-1) increased from
12.5 to 14.8 m3 ha-1 in control plots (no amendment) during 1st year of experimentation
(2011-12). In 2nd year (2012-13), bole volume of trees increased from 14.8 to 17.8 m3 ha-1 in
control plots. However, with application of amendments, there was general trend in
increment in bole volume of trees (A. nilotica). Bole volume of trees increased from 17.7 to
18.9 m3 ha-1 during 1st year (2011-12) in plots applied with treatment (Gypsum @ GR 100%
+ FYM 10 Mg ha-1). In 2nd year (2012-13), bole volume of trees increased from 18.9 to 21.4
m3 ha-1 in such plots. In case of sole tree plantation, bole volume increased from 14.5 to 16.4
m3 ha-1 during 1st year (2011-12) and 16.4 to 20.5 m3 ha-1 in 2nd year (2012-13).
Bole volume of trees (m3 ha-1) in Eucalyptus-based agroforestry system increased
from 29.9 to 33.8 m3 ha-1 in control plots in 1st year (2011-12). In 2nd year (2012-13), bole
volume of trees increased from 33.8 to 41.1 m3 ha-1 in control plots. However with
application of soil amendments, there was general trend in increment in bole volume of trees
(E. camaldulensis). In case of application of treatment (Gypsum @ GR 100% + FYM 10 Mg
ha-1), bole volume of trees increased from 22.2 to 25.6 m3 ha-1 during 1st year (2011-12). In
2nd year, trees followed the same trend and bole volume increased from 25.6 to 29.5 m3 ha-1.
In sole tree plantation, bole volume of trees increased from 19.6 to 23.4 m3 ha-1 during 1st
year (2011-12). In 2nd year (2012-13), bole volume of trees increased from 23.4 to 27.9 m3
ha-1.
Overall comparison of fertility factor in these systems showed that bole volume was
significantly improved with application of soil amendments in agroforestry systems as it
progressively increased in all the treatments where soil amendments were applied as
compared to control (no amendment) and sole plantations of these tree species.
130
Table 4.28 Effect of amendments on bole volume (m3 ha-1) grown in sole field, Acacia-
based and Eucalyptus-based agroforestry systems.
Treatments
Bole Volume (m3 ha-1)
Acacia nilotica Eucalyptus camaldulensis
2011 2012 2013 2011 2012 2013
Control (To)
12.5±2.57 14.8±3.78 17.8±3.24 29.9±3.06 33.8±2.91 41.1±0.82
Gypsum @ GR
100%
(T1)
11.4±3.04 13.9±3.81 17.2±4.78 25.3±2.96 29.4±2.34 33.1±2.07
FYM 20 Mg
ha-1 (T2) 16.6±3.96 19.6±3.36 23.4±1.98 23.6±3.04 26.9±2.14 31.3±3.35
Gypsum @ GR
50%+FYM 10 Mg
ha-1(T3)
16.6±1.97 19.1±0.95 22.7±2.96 20.5±2.62 24.3±2.90 29.5±1.13
Gypsum @ GR
100%+FYM 10
Mg ha-1 (T4)
17.6±2.73 18.9±3.79 21.4±1.95 22.3±2.59 25.6±2.43 29.5±3.71
Sole Tree Block 14.5±2.93 16.4±1.14 20.5±1.47 19.6±2.35 23.5±3.03 27.9±3.10
131
4.2.2.2 Mean Annual Increment in wood production
The results of mean annual increment (MAI) in tree bole volume (Table 4.29)
showed significant interactive effect of varying levels of gypsum and farm yard manure on
tree wood volume in Acacia and Eucalyptus based alley cropping systems.
In Acacia-based agroforestry system, current annual increment (CAI) in bole volume
of trees was 1.26 m3 ha-1 yr-1 in control plots during 1st year of experimentation (2011-12). In
2nd year (2012-13), CAI in bole volume of trees was 2.45 m3 ha-1 in control plots. Hence the
calculated mean annual increment (MAI) was 1.85 m3 ha-1 yr-1 in control plots (no
amendment). A general positive trend in MAI of bole volume of trees (A. nilotica) with
application of amendments was observed. In case of application of treatment (Gypsum @ GR
100% + FYM 10 Mg ha-1), CAI in bole volume of trees was 2.92 m3 ha-1 yr-1 during 1st year
(2011-12), while in 2nd year (2012-13), CAI in bole volume of trees was 3.84 m3 ha-1 yr-1.
Hence, MAI in such treated plots was recorded as 3.38 m3 ha-1 yr-1. In case of sole tree
plantation, CAI in bole volume was 1.43 m3 ha-1 yr-1 during 1st year (2011-12) whereas in 2nd
year (2012-13), CAI in bole volume of trees was 2.34 m3 ha-1 yr-1. MAI was 1.88 m3 ha-1 yr-1
in sole plantation plots.
In Eucalyptus-based agroforestry system, CAI in bole volume of trees was 3.33 m3 ha-
1 yr-1 in 1st year and for 2nd year (2012-13) 3.91 m3 ha-1 yr-1 in bole volume of trees was in
control plots. MAI was recorded as 3.62 m3 ha-1 yr-1 in control plots. A general progressive
trend was observed in MAI of bole volume of trees (E. camaldulensis) with application of
amendments. In case of application of treatment (Gypsum @ GR 100% + FYM 10 Mg ha-1),
CAI in bole volume of trees was 3.99 m3 ha-1 yr-1 during 1st year (2011-12) and 7.27 m3 ha-1
yr-1 in 2nd year (2012-13) with mean annual increment (MAI) was 5.63 m3 ha-1 yr-1. In case
of sole Eucalyptus tree plantation, CAI in bole volume was 3.24 m3 ha-1 yr-1 for 1st year
(2011-12) and 4.41 m3 ha-1 yr-1 for 2nd year (2012-13). The calculated MAI in sole plantation
plots was 3.82 m3 ha-1 yr-1.
132
Table 4.29 Effect of amendments on mean annual increment (m3 ha-1 yr-1) in wood production of trees grown in sole field and
agroforestry systems
Treatment
m3 ha-1 yr-1
Acacia nilotica E. camaldulensis
CAI
(2011-12)
CAI
(2012-13)
MAI Annual
wood
addition
(Kg)
CAI
(2011-12)
CAI
(2012-13)
MAI Annual
wood
addition
(Kg)
Control (To)
1.26 2.45 1.85d 1496 3.33 3.91 3.62e 2465
Gypsum GR 100% (T1)
2.29 3.01 2.65c 2144 4.13 3.69 3.91d 2662
FYM 20 Mg ha-1 (T2)
1.93 4.12 3.03b
2451 3.87 4.45 4.16b 2833
Gypsum GR 50%+FYM 10 Mg
ha-1(T3)
2.53 3.58 3.05b 2467 3.85 5.13 4.49b
3058
Gypsum GR 100%+FYM 10 Mg
ha-1 (T4)
2.92 3.84 3.38a 2734 3.99 7.27 5.63a
3834
Sole Tree Block 1.43 2.34 1.88d 1521
3.24 4.41 3.82c 2601
Means values followed by different letter(s) in each category are statistically different using least significantly difference (LSD) test at 5% level of probability.
133
4.2.3 Annual biomass productivity of different systems
Annual biomass productivity (kg ha-1 yr-1) of all the systems (Table 4.30) showed
significant interactive effect of varying levels of soil amendments in open field and
agroforestry systems.
In open field conditions, annual biomass productivity of para grass was 7940 kg in
control plots (no amendment). With addition of different soil amendments, biomass
productivity responded positively and its highest level was achieved in treatment (Gypsum
@GR 100% + FYM 10 Mg ha-1) where biomass productivity was 12800 kg ha-1 yr-1 (61.2%
higher).
In Acacia-based agroforestry system, the lowest annual biomass productivity of para
grass component was 6940 kg ha-1 yr-1, whereas that of woody component was 1496 kg ha-1
yr-1 in control plots (no amendment) with total biomass productivity was 8436 kg ha-1 yr-1.
Biomass productivity of both the components of the system increased progressively with
application of different levels of amendments. The highest annual biomass productivity of
para grass component was 11610 kg ha-1 yr-1, whereas that of woody component was 2734 kg
ha-1 yr-1 in plots applied with treatment (Gypsum @GR 100% + FYM 10 Mg ha -1). Hence,
total biomass productivity of Acacia-based agroforestry system was 14344 kg ha-1 yr-1 (70%
higher). In case of sole plantation of A. nilotica, total biomass productivity was observed as
1521 kg ha-1 yr-1.
Eucalyptus-based agroforestry system, annual biomass productivity of para grass
component was 5970 kg ha-1 yr-1 whereas that of woody component was 2465 kg ha-1 yr-1 in
control plots (no amendment), hence total biomass productivity of the system was 8615 kg
ha-1 yr-1. Biomass productivity of both the components of the system increased progressively
with application of different levels of amendments. The highest annual biomass productivity
of para grass component was 10830 kg ha-1 yr-1 whereas,` that of woody component was
3834 kg ha-1 yr-1 in plots applied with treatment (Gypsum @GR 100% + FYM 10 Mg ha-1).
Hence total biomass productivity of Eucalyptus-based agroforestry system was 14664 kg ha-1
(70.2% higher) yr-1. In case of sole plantation of E. camaldulensis, total biomass productivity
was observed as 2601 kg ha-1 yr-1.
134
Table 4.30 Effect of amendments on aggregate biomass productivity (kg ha-1 yr-1) of sole plantation, Acacia-based and
Eucalyptus-based agroforestry systems
Treatments
Biomass production (kg ha-1 yr-1)
Open field
(Sole cropping)
Acacia-based
agroforestry system
Eucalyptus-based
agroforestry system
Para grass Wood Total Para grass Wood Total Para grass Wood Total
Control (To)
7940 - 7940d 6940 1496 8436d 5970 2465 8615d
Gypsum GR 100% (T1)
9440 - 9440c 8530 2144 10674c
7390
2662 10052c
FYM 20 Mg ha-1 (T2)
10800 - 10800b 9620 2451 11741b
8170
2833 11003b
Gypsum GR 50% +
FYM 10 Mg ha-1(T3)
11300 - 11300b 10530 2467 12071b 9430
3058 12515b
Gypsum GR 100% +
FYM 10 Mg ha-1 (T4)
12800 - 12800a 11610 2734 14344a 10830
3834 14664a
Sole Tree Block NA NA NA - 1521 1521e - 2601 2601e
Means values followed by different letter(s) in each category are statistically different using least significantly difference (LSD) test at 5% level of probability.
135
4.2.4 Variations in soil chemical properties under sole and alley cropping systems
Cultivation of plants either in open field or in agroforestry systems strongly
influences chemical properties of soil due to root physical/mechanical action, root exudation,
change in evapotranspiration pattern and nutrient recycling by plants. Among these chemical
properties, pH, electrical conductivity (EC), and sodium adsorption ratio (SAR) are of main
concern from soil amelioration point of view in agroforestry systems established in salt-
affected soils. Results obtained for above mentioned soil chemical parameters from the
present study are presented in following sections.
4.2.4.1 Soil pH
Data regarding pH of soil profile (0-150 cm) in open field, Acacia-based and
Eucalyptus-based alley cropping systems is shown in Fig. 6 and described in tables 4.31 to
4.33. In all the systems (open field, Acacia-based and Eucalyptus-based systems), pre-
experimentation analysis of soil properties regarding pH values showed difference at various
depths (0-15, 15-30, 30-60, 60-90, 90-120 and 120-150 cm) in soil profile.
In open field system, soil pH (Table 4.31) recorded at the initiation of study was 8.54
in control (no amendment) at 0-15 cm. With the passage of time, soil pH decreased to 8.48
due to cultivation of para grass for two successive years. Similarly, soil pH at the depth of
15-30 cm increased from 8.58 to 8.55 with cultivation of para grass. Soil pH also showed
variation with application of amendments and the highest reduction was found in upper layer
(0-15 cm) in plots applied with treatment (Gypsum @ GR 100% +FYM 10 Mg ha-1). Variation
in soil pH in deep layers from 30 to 150 cm as affected with application of different
amendments is shown in table. Generally pH increased in deeper layers due to leaching of
salts from the upper layers.
In Acacia-based systems, soil pH (Table 4.32) in respective control (no amendment)
at the start of experimentation was 8.59 (0-15 cm) which decreased to 8.50 with cultivation
of para grass for two successive years. At the depth of 15-30 cm, soil pH was 8.56 which
decreased to 8.49 with cultivation of para grass. Soil pH also showed variation with
application of amendments and the highest reduction was observed in upper layers (0-15 and
15-30 cm) in treatment plots applied with treatment (Gypsum @ GR 100% +FYM 10 Mg ha-1).
136
In case of sole plantation, minor reduction was found in upper 0-15 and 15-30 cm,
respectively. Variations in soil pH in deep layers from 30 to 150 cm as affected with
application of different amendments are shown in table. Generally pH increased in deeper
layers due to leaching of salts from the upper layers.
In Eucalyptus-based systems, soil pH (Table 4.33) in their respective control
treatment (no amendment) at the start of experimentation was 8.66 (0-15 cm) which
decreased to 8.62 with cultivation of para grass for two successive years. At the depth of 15-
30 cm, pH was 8.48 which decreased to 8.44 with the cultivation of para grass. Soil pH also
showed variation with application of amendments and the highest reduction was found in
upper layers (0-15, 15-30 cm, respectively) in treatment plots applied with (Gypsum @ GR
100% +FYM 10 Mg ha-1). In case of sole plantation, reduction of soil pH was slightly reduced
in upper (0-15 cm) and lower (15-30 cm) soil layers. Variations in soil pH in other deep
layers from 30 to 150 cm as affected with application of different amendments are shown in
table. Generally, pH increased in deeper layers possibly due to leaching of salts from the
upper layers.
In agroforestry systems, more reduction in pH was found in Acacia-based systems as
compared to Eucalyptus-based systems. Application of farm yard manure alone or in
combination with gypsum also affected pH in both the systems and more prominently in
Acacia-based systems.
137
Figure 6. Effect of different soil amendments on soil pH under open field, Acacia- and
Eucalyptus-based alley cropping systems
-3
-2
-1
0
T0 T1 T2 T3 T4 T5
0 to 15 cm
0
1
2
3
4
T0 T1 T2 T3 T4 T5
60 to 90 cm
-3
-2
-1
0
T0 T1 T2 T3 T4 T5
16 to 30 cm
0
1
2
3
T0 T1 T2 T3 T4 T5
90 to 120 cm
-2
-1
0
T0 T1 T2 T3 T4 T5
30 to 60 cm
Open crop field Acacia based alley
Eucalyptus-based alley
0
1
2
T0 T1 T2 T3 T4 T5
120 to 150 cm
Open crop field Acacia based alley
Eucalyptus-based alley
138
Table 4.31 Effect of amendments on soil pH in open field (sole cropping).
Treatment Depth
(cm)
Para grass growing in open field
May
2011
Nov
2011
May
2012
Nov
2012
% change
over initial
value
Control (To)
0-15 8.54 8.49 8.53 8.48 -0.70
16-30 8.58 8.56 8.57 8.55 -0.35
30-60 8.61 8.55 8.53 8.49 -1.39
60-90 8.45 8.53 8.49 8.67 2.60
90-120 8.6 8.68 8.64 8.74 1.63
120-150 8.57 8.77 8.71 8.74 1.98
Gypsum @ GR 100% (T1)
0-15 8.57 8.61 8.57 8.49 -0.93
16-30 8.47 8.44 8.44 8.43 -0.47
30-60 8.53 8.46 8.41 8.36 -1.99
60-90 8.35 8.45 8.38 8.5 1.80
90-120 8.21 8.33 8.31 8.37 1.95
120-150 8.37 8.4 8.38 8.46 1.08
FYM 20 Mg ha-1
(T2)
0-15 8.62 8.58 8.67 8.57 -0.58
16-30 8.52 8.48 8.46 8.41 -1.29
30-60 8.57 8.54 8.51 8.53 -0.47
60-90 8.34 8.37 8.38 8.62 3.36
90-120 8.35 8.46 8.41 8.53 2.16
120-150 8.49 8.58 8.54 8.62 1.53
Gypsum @ GR50%+FYM 10 Mg ha-1
(T3)
0-15 8.58 8.47 8.5 8.44 -1.63
16-30 8.56 8.44 8.43 8.41 -1.75
30-60 8.56 8.51 8.47 8.42 -1.64
60-90 8.38 8.43 8.41 8.51 1.55
90-120 8.4 8.46 8.43 8.55 1.79
120-150 8.41 8.48 8.45 8.49 0.95
Gypsum @ GR 100% +FYM 10 Mg ha-1
(T4)
0-15 8.59 8.52 8.54 8.41 -2.10
16-30 8.46 8.41 8.39 8.33 -1.54
30-60 8.49 8.45 8.41 8.36 -1.53
60-90 8.37 8.42 8.39 8.47 1.19
90-120 8.46 8.51 8.47 8.58 1.42
120-150 8.51 8.52 8.5 8.64 1.53
139
Table 4.32 Effect of amendments on soil pH in Accaia-para grass based alley cropping
systems.
Treatment Depth
(cm)
Para grass growing in open field
May
2011
Nov
2011
May
2012
Nov
2012
% change
over initial
value
Control (To)
0-15 8.59 8.34 8.47 8.5 -1.05
16-30 8.56 8.57 8.51 8.49 -0.82
30-60 8.6 8.58 8.53 8.46 -1.63
60-90 8.48 8.56 8.51 8.61 1.53
90-120 8.59 8.64 8.62 8.71 1.40
120-150 8.57 8.65 8.61 8.72 1.75
Gypsum @ GR 100% (T1)
0-15 8.65 8.61 8.64 8.55 -1.16
16-30 8.47 8.43 8.27 8.38 -1.06
30-60 8.53 8.48 8.46 8.39 -1.64
60-90 8.44 8.51 8.46 8.58 1.66
90-120 8.52 8.55 8.57 8.6 0.94
120-150 8.58 8.63 8.61 8.68 1.17
FYM 20 Mg ha-1
(T2)
0-15 8.61 8.55 8.55 8.49 -1.39
16-30 8.59 8.53 8.54 8.48 -1.28
30-60 8.58 8.5 8.46 8.41 -1.98
60-90 8.55 8.61 8.58 8.64 1.05
90-120 8.51 8.63 8.55 8.61 1.18
120-150 8.59 8.66 8.62 8.68 1.05
Gypsum @ GR50%+FYM 10 Mg ha-1
(T3)
0-15 8.53 8.27 8.64 8.41 -1.41
16-30 8.49 8.55 8.52 8.37 -1.41
30-60 8.51 8.44 8.42 8.4 -1.29
60-90 8.47 8.52 8.49 8.56 1.06
90-120 8.48 8.55 8.51 8.6 1.42
120-150 8.53 8.63 8.56 8.61 0.94
Gypsum @ GR 100% +FYM 10 Mg ha-1
(T4)
0-15 8.57 8.46 8.47 8.35 -2.57
16-30 8.67 8.61 8.63 8.42 -2.88
30-60 8.51 8.48 8.45 8.4 -1.29
60-90 8.37 8.41 8.38 8.47 1.19
90-120 8.44 8.49 8.48 8.55 1.30
120-150 8.47 8.58 8.54 8.63 1.89
Sole plantation Acacia nilotica
0-15 8.53 8.59 8.55 8.48 -0.59
16-30 8.58 8.61 8.54 8.51 -0.82
30-60 8.55 8.46 8.48 8.46 -1.05
60-90 8.56 8.6 8.57 8.63 0.82
90-120 8.51 8.63 8.56 8.61 1.18
120-150 8.58 8.66 8.59 8.68 1.17
140
Table 4.33 Effect of amendments on soil pH in Eualyptus-para grass based alley
cropping systems.
Treatment Depth
(cm)
Para grass growing in open field
May
2011
Nov
2011
May
2012
Nov
2012
% change
over initial
value
Control (To)
0-15 8.66 8.64 8.64 8.62 -0.46
16-30 8.48 8.44 8.37 8.44 -0.47
30-60 8.5 8.47 8.45 8.48 -0.24
60-90 8.38 8.43 8.4 8.45 0.84
90-120 8.48 8.53 8.49 8.56 0.94
120-150 8.55 8.59 8.57 8.61 0.70
Gypsum @ GR 100% (T1)
0-15 8.61 8.46 8.51 8.49 -1.39
16-30 8.55 8.63 8.55 8.51 -0.47
30-60 8.51 8.59 8.51 8.49 -0.24
60-90 8.48 8.51 8.53 8.53 0.59
90-120 8.52 8.59 8.55 8.62 1.17
120-150 8.5 8.47 8.49 8.55 0.59
FYM 20 Mg ha-1
(T2)
0-15 8.48 8.49 8.46 8.44 -0.47
16-30 8.47 8.54 8.58 8.42 -0.59
30-60 8.44 8.42 8.41 8.41 -0.36
60-90 8.32 8.36 8.31 8.39 0.84
90-120 8.31 8.39 8.34 8.41 1.20
120-150 8.42 8.44 8.41 8.47 0.59
Gypsum @ GR50%+FYM
10 Mg ha-1
(T3)
0-15 8.54 8.57 8.53 8.47 -0.82
16-30 8.67 8.61 8.63 8.58 -1.04
30-60 8.64 8.59 8.57 8.56 -0.93
60-90 8.55 8.57 8.54 8.63 0.94
90-120 8.54 8.61 8.55 8.59 0.59
120-150 8.51 8.57 8.54 8.62 1.29
Gypsum @ GR 100% +FYM 10
Mg ha-1
(T4)
0-15 8.63 8.57 8.51 8.49 -1.62
16-30 8.53 8.43 8.39 8.41 -1.41
30-60 8.5 8.47 8.45 8.39 -1.29
60-90 8.37 8.41 8.41 8.43 0.72
90-120 8.44 8.47 8.46 8.52 0.95
120-150 8.47 8.55 8.51 8.57 1.18
Sole plantation Eucalyptus camaldulensis
0-15 8.59 8.61 8.63 8.58 -0.12
16-30 8.48 8.51 8.47 8.45 -0.35
30-60 8.52 8.48 8.46 8.45 -0.82
60-90 8.49 8.53 8.55 8.55 0.71
90-120 8.58 8.65 8.61 8.67 1.05
120-150 8.68 8.78 8.7 8.75 0.81
141
4.2.4.2 Soil electrical conductivity
Data regarding electrical conductivity (EC) of soil profile (0-150 cm) in open
field, Acacia-based and Eucalyptus-based alley cropping systems is shown in Fig. 7 and
described in tables 4.34 to 4.36. In all the systems (open field, Acacia-based and Eucalyptus-
based systems), pre-experimentation analysis of soil electrical conductivity showed variation
at different depths (0-15, 15-30, 30-60, 60-90, 90-120 and 120-150 cm).
In open field system, pre-experimentation soil EC in control plots (no amendment)
was 13.1 dS m-1 (0-15 cm) which increased to 11.86 dS m-1 with cultivation of para grass for
two successive years (Table 4.34). Soil EC also showed variation with application of
amendments and the highest reduction was found in upper layer (0-15 cm) in plots applied
with treatment (Gypsum @ GR 100% +FYM 10 Mg ha-1 ). Variation in soil EC in deep layers
from 30 to 150 cm as affected with application of different amendments are shown in table.
Generally, electrical conductivity increased in deeper layers of soils due to leaching of salts
from the surface layer(s).
In Acacia-based systems, soil EC in respective control plots (no amendment) at the
start of experimentation was 15.25 dS m-1 (0-15 cm) which decreased to 13.52 dS m-1 with
cultivation of para grass for two years (Table 4.35). At the depth of 15-30 cm, soil EC was
12.27 dS m-1 which decreased to 9.87 dS m-1 with cultivation of para grass. Soil EC also
showed variation with application of amendments and the highest reduction was found in
upper layers (0-15, 15-30 cm respectively) in plots applied with (Gypsum @ GR 100%
+FYM 10 Mg ha-1). In case of sole plantation, reduction in electrical conductivity was
observed in upper 0-15 and 15-30 cm, respectively. Variation in soil EC at depths up to 150
cm as affected with application of different amendments as shown in table revealed that salts
leached from the soil surface to deeper layers of soil profile to different extent.
142
In Eucalyptus-based systems, pre-experimentation soil EC in respective control (no
amendment) was 14.07 dS m-1 (0-15 cm) which decreased to 12.89 dS m-1 with cultivation
of para grass for two successive years (Table 4.36). At the depth of 15-30 cm, soil EC was
13.18 dS m-1 which decreased to 11.76 dS m-1 with cultivation of para grass. Soil EC also
showed variation with application of amendments and the highest reduction was observed in
upper layers (0-15, 15-30 cm, respectively) in plots applied with (Gypsum @ GR 100%
+FYM 10 Mg ha-1 ). Variation in soil EC at other depths up to 150 cm as affected with
application of different amendments, given in table, showed that salts leached from the
surface to deeper layers of soil profile.
In case of sole plantations of A. nilotica and E. camaldulensis, minor reduction in EC
was observed in upper 0-15 and 15-30 cm, respectively. The restoration process was more
effective in A. nilotica as compared to E. camaldulensis plantations.
143
Figure 7. Effect of different soil amendments on soil electrical conductivity (EC) under
open field, Acacia- and Eucalyptus-based alley cropping systems
-40
-30
-20
-10
0
T0 T1 T2 T3 T4 T5
0 to 15 cm
-20
0
20
40
T0 T1 T2 T3 T4 T5
60 to 90 cm
-40
-30
-20
-10
0
T0 T1 T2 T3 T4 T5
16 to 30 cm
-20.0
0.0
20.0
40.0
60.0
T0 T1 T2 T3 T4 T5
90 to 120 cm
-40.0
-20.0
0.0
T0 T1 T2 T3 T4 T5
30 to 60 cm
Open crop field Acacia based alley
Eucalyptus-based alley
-20
0
20
40
T0 T1 T2 T3 T4 T5
120 to 150 cm
Open crop field Acacia based alley
Eucalyptus-based alley
144
Table 4.34 Effect of amendments on soil electrical conductivity in sole cropping systems
Treatment Depth
(cm)
Open crop field
May
2011
Nov
2011
May
2012
Nov
2012
% change
over initial
value
Control (To)
0-15 13.1 11.28 12.33 11.86 -9.5 16-30 14.52 12.79 13.61 12.96 -10.7 30-60 17.37 13.27 15.29 13.09 -24.6 60-90 18.36 23.14 20.96 21.17 15.3 90-120 16.34 20.08 18.43 21.15 29.4
120-150 24.37 26.28 26.27 27.45 12.6
Gypsum @ GR 100% (T1)
0-15 17.45 15.27 13.46 14.7 -15.8 16-30 14.21 12.55 14.37 12 -15.6 30-60 17.82 14.58 15.37 14.33 -19.6 60-90 13.29 17.56 15.23 16.37 23.2 90-120 14.07 16.56 13.87 17.33 23.2
120-150 12.58 16.28 14.37 14.45 14.9
FYM 20 Mg ha-1
(T2)
0-15 15.42 14.26 12.69 13.52 -12.3 16-30 11.24 12.53 13.07 9.42 -16.2 30-60 12.59 10.51 10.97 11.04 -12.3 60-90 9.78 10.03 11.39 13.1 33.9 90-120 11.56 13.97 11.08 15.37 33.0
120-150 14.37 18.37 16.81 18.07 25.7
Gypsum @ GR50%+FYM 10 Mg ha-1
(T3)
0-15 14.26 10.46 11.26 11.45 -19.7 16-30 19.54 19.77 10.02 17.6 -9.9 30-60 22.46 18.46 17.26 17.45 -22.3 60-90 17.29 22.94 19.37 20.01 15.7 90-120 22.37 23.61 19.34 25.1 12.2
120-150 22.17 26.37 23.97 28.54 28.7
Gypsum @ GR 100% +FYM 10 Mg ha-1
(T4)
0-15 18.7 15.36 12.98 14.89 -20.4 16-30 15.75 13.86 10.55 12.29 -22.0 30-60 19.55 16.29 17.46 14.26 -27.1 60-90 16.55 19.95 17.37 18.55 12.1 90-120 16.97 20.67 18.33 20.37 20.0
120-150 17.92 18.74 16.37 20.24 12.9
145
Table 4.35 Effect of amendments on soil electrical conductivity in Accaia-para grass
based alley cropping systems.
Treatment Depth
(cm)
Accaia-para grass based alley cropping systems.
May
2011
Nov
2011
May
2012
Nov
2012
% change
over initial
value
Control (To)
0-15 15.25 16.42 15.27 13.52 -11.3 16-30 12.27 11.86 12.55 9.87 -19.6 30-60 13.46 12.37 11.36 10.92 -18.9 60-90 10.17 14.37 12.17 13.14 29.2 90-120 14.3 17.09 16.55 17.22 20.4
120-150 11.58 16.49 13.28 13.05 12.7
Gypsum @ GR 100% (T1)
0-15 16.02 16.55 14.29 11.76 -26.6 16-30 16.76 14.79 16.87 12.26 -26.8 30-60 15.84 13.82 12.33 11.07 -30.1 60-90 14.85 16.89 13.97 18.27 23.0 90-120 13.07 14.37 12.85 15.36 17.5
120-150 13.91 17.35 15.53 17.37 24.9
FYM 20 Mg ha-1
(T2)
0-15 15.88 15.79 15.34 12.54 -21.0 16-30 12.26 12.46 14.09 9.47 -22.8 30-60 17.61 16.33 14.43 13.27 -24.6 60-90 12.83 14.51 14.68 16.45 28.2 90-120 16.57 22.56 18.69 24.37 47.1
120-150 18.64 22.04 20.17 23.87 28.1
Gypsum @ GR50%+FYM
10 Mg ha-1
(T3)
0-15 17.82 16.24 15.26 12.87 -27.8 16-30 16.76 12.77 11.25 11.54 -31.1 30-60 17.68 15.67 14.07 12.25 -30.7 60-90 16.22 19.25 18.55 21.38 31.8 90-120 17.11 22.16 19.37 24.15 41.1
120-150 15.44 17.56 16.24 18.1 17.2
Gypsum @ GR
100% +FYM 10 Mg ha-1
(T4)
0-15 19.26 14.26 12.69 13.07 -32.1 16-30 17.55 17.55 18.07 11.76 -33.0 30-60 18.76 16.55 15.12 14.09 -24.9 60-90 16.21 19.38 17.66 21.37 31.8 90-120 16.44 19.39 18.47 18.9 15.0
120-150 14.55 18.51 17.81 16.2 11.3
Sole plantation Acacia nilotica
0-15 14.02 12.55 14.55 12.76 -9.0 16-30 12.36 12.53 11.37 10.89 -11.9 30-60 13.88 11.74 10.87 11.33 -18.4 60-90 14.28 16.23 14.87 17.5 22.5 90-120 10.07 12.71 11.87 12.84 27.5
120-150 12.28 13.54 12.85 14.36 16.9
146
Table 4.36 Effect of amendments on soil electrical conductivity in Eucalyptus-para grass
based alley cropping systems.
Treatment Depth
(cm)
Eucalyptus-para grass based alley cropping systems
May
2011
Nov
2011
May
2012
Nov
2012
% change
over initial
value
Control (To)
0-15 14.07 13.85 12.74 12.89 -8.4
16-30 13.18 12.67 13.46 11.76 -10.8
30-60 15.56 14.74 13.33 12.85 -17.4
60-90 15.82 17.77 16.82 18.67 18.0
90-120 18.67 20.81 19.84 22.54 20.7
120-150 21.26 24.57 22.51 26.57 25.0
Gypsum @ GR 100% (T1)
0-15 15.48 14.23 13.52 13 -16.0
16-30 15.23 14.79 13.54 12.96 -14.9
30-60 17.55 15.73 14.27 13.86 -21.0
60-90 14.17 16.07 15.12 18.37 29.6
90-120 19.54 21.15 20.24 23.06 18.0
120-150 20.95 24.17 22.87 25.83 23.3
FYM 20 Mg ha-1
(T2)
0-15 14.45 12.37 11.54 12.59 -12.9
16-30 14.28 14.26 12.33 11.86 -16.9
30-60 16.23 15.07 13.95 12.26 -24.5
60-90 16.37 18.95 17.21 20.35 24.3
90-120 22.81 26.54 24.81 28.77 26.1
120-150 17.22 20.16 18.21 22.54 30.9
Gypsum @ GR50%+FYM 10 Mg ha-1
(T3)
0-15 15.64 13.55 12.64 12.45 -20.4
16-30 18.23 16.38 15.27 14.27 -21.7
30-60 20.54 18.05 16.28 15.22 -25.9
60-90 20.87 21.37 23.26 19.55 -6.3
90-120 23.87 25.44 26.77 22.42 -6.1
120-150 26.22 27.27 30.82 25.61 -2.3
Gypsum @ GR 100% +FYM 10 Mg ha-1
(T4)
0-15 18.52 17.54 12.19 14.37 -22.4
16-30 16.38 14.31 12.57 12.41 -24.2
30-60 18.75 17.08 15.24 13.11 -30.1
60-90 18.21 21.07 19.55 22.67 24.5
90-120 15 19.34 16.27 18 20.0
120-150 19.37 25.11 23.51 24.57 26.8
Sole plantation Euxalyptus camaldulensis
0-15 13.45 12.27 13.46 12.76 -5.1
16-30 14.07 12.36 12.98 12.89 -8.4
30-60 18.36 19.54 16.23 15.42 -16.0
60-90 18.95 20.28 19.04 21.31 12.5
90-120 19.26 23.01 20.95 25.17 30.7
120-150 24.67 26.95 23.17 28.39 15.1
147
4.2.4.3 Sodium adsorption ratio
Data regarding sodium adsorption ratio (SAR) of soil profile (0-150 cm) in open
field, Acacia-based and Eucalyptus-based alley cropping systems is shown in Fig. 8 and
described in tables 4.37 to 4.39. In all the systems, pre-experimentation analysis of SAR
showed variation at different depths (0-15, 15-30, 30-60, 60-90, 90-120 and 120-150 cm).
In open field system, pre-experimentation soil SAR in control plots (no
amendment) was 58.7 (0-15 cm) which decreased to 53.7 with cultivation of para grass for
two successive years(Table 4.34). At the depth of 15-30 cm, soil SAR was 54.3 which
increased to 49.6 with cultivation of wheat. Soil SAR also showed variation with application
of amendments and the highest reduction was observed in upper layers (0-15 cm and 15-30
cm respectively) in plots applied with (Gypsum @ GR 100% +FYM 10 Mg ha-1 ). Variation in
soil SAR in deep layers up to 150 cm as affected with application of different amendments
showed that SAR increased in deeper layer of soil profile to varying magnitude.
In Acacia-based systems, soil SAR in respective control plots (no amendment) at
the start of experimentation was 54.4 (0-15 cm) which decreased to 43.3 with cultivation of
para grass for two years(Table 4.21). At the depth of 15-30 cm, soil SAR was 54.75 which
decreased to 47.82 with cultivation of para grass. Soil SAR also showed variation with
application of amendments and the highest reduction was observed in upper layers (0-15 and
15-30 cm) in plots applied with treatment (Gypsum @ GR 100% +FYM 10 Mg ha-1 ). In case
of sole plantation, reduction in pH was observed in upper 0-15 and 15-30 cm, respectively.
Variation in soil SAR in deep layers up to 150 cm as affected with application of different
amendments showed that SAR decreased in upper layers to varying levels. In case of sole
plantation, reduction in SAR was observed in upper 0-15 and 15-30 cm, respectively.
148
In Eucalyptus based systems, soil SAR (Table 4.22) in respective control (no
amendment) at the start of experimentation was 57.3 (0-15 cm) which decreased to 48.7 with
cultivation of para grass for two years. At the depth of 15-30 cm, soil SAR was 67.1 which
decreased to 48.7 with cultivation of para grass. Soil SAR also showed variation with
application of amendments and the highest reduction was observed in upper layers (0-15, 15-
30 cm respectively) in plots applied with treatment (Gypsum @ GR 100% +FYM 10 Mg ha-1).
Variation in SAR in deep layers up to 150 cm as affected with application of different
amendments has shown that SAR decreased in upper layers to varying levels. In case of sole
plantation, minor reduction in SAR was observed in upper 0-15 and 15-30 cm, respectively.
149
Figure 8. Effect of different soil amendments on soil sodium adsorption ratio (SAR)
under open field, Acacia- and Eucalyptus-based alley cropping systems
-40
-30
-20
-10
0
T0 T1 T2 T3 T4 T5
0 to 15 cm
0
5
10
15
20
T0 T1 T2 T3 T4 T5
60 to 90 cm
-40
-30
-20
-10
0
T0 T1 T2 T3 T4 T5
16 to 30 cm
0
10
20
30
T0 T1 T2 T3 T4 T5
90 to 120 cm
-20
-10
0
T0 T1 T2 T3 T4 T5
30 to 60 cm
Open crop field Acacia based alley
Eucalyptus-based alley
-20
0
20
40
T0 T1 T2 T3 T4 T5
120 to 150 cm
Open crop field Acacia based alley
Eucalyptus-based alley
150
Table 4.37 Effect of amendments on soil sodium adsorption ratio (SAR) in open field
conditions.
Treatment Depth
(cm)
Para grass grown in open field
May
2011
Nov
2011
May
2012
Nov
2012
% change
over initial
value
Control (To)
0-15 58.71 53.22 48.63 53.77 -8.4 16-30 54.28 51.44 53.74 49.59 -8.6 30-60 58.35 56.82 55.07 52.55 -9.9 60-90 61.07 64.32 62.84 67.21 10.1 90-120 47.28 51.23 49.87 53.29 12.7
120-150 37.55 43.67 39.54 45.54 21.3
Gypsum @ GR 100% (T1)
0-15 64.51 57.55 53.85 55.73 -13.6 16-30 58.74 55.72 52.88 49.71 -15.4 30-60 57.69 55.37 53.67 51.86 -10.1 60-90 53.67 57.38 56.11 60.43 12.6 90-120 39.37 46.2 43.22 48.16 22.3
120-150 43.27 48.69 45.19 50.17 15.9
FYM 20 Mg ha-1
(T2)
0-15 63.22 54.71 49.23 51.45 -18.6 16-30 57.64 49.35 44.74 45.79 -20.6 30-60 54.19 47.56 49.64 46.08 -15.0 60-90 46.55 51.97 49.18 53.12 14.1 90-120 53.16 56.21 55.37 57.21 7.6
120-150 50.04 53.92 51.62 55.37 10.7
Gypsum @ GR50%+FYM 10 Mg ha-1
(T3)
0-15 62.71 55.75 49.35 48.77 -22.2 16-30 51.83 47.25 42.76 39.18 -24.4 30-60 56.24 54.55 51.82 48.62 -13.5 60-90 41.09 43.52 42.57 45.42 10.5 90-120 43.77 46.46 45.07 47.12 7.7
120-150 42.55 47.63 45.21 49.43 16.2
Gypsum @ GR 100% +FYM 10 Mg ha-1
(T4)
0-15 72.81 65.24 56.78 54.83 -24.7 16-30 61.85 58.77 53.16 46.52 -24.8 30-60 58.66 55.28 52.07 48.56 -17.2 60-90 49.07 52.18 50.15 56.12 14.4 90-120 52.94 57.64 55.95 59.3 12.0
120-150 50.37 53.69 51.88 55.38 9.9
151
Table 4.38 Effect of amendments on soil sodium adsorption ratio (SAR) Acacia-based
agroforestry systems
Treatment Depth
(cm)
Acacia-based agroforestry systems
May
2011
Nov
2011
May
2012
Nov
2012
% change
over initial
value
Control (To)
0-15 54.42 52.67 48.54 43.31 -20.4 16-30 54.75 47.86 51.55 47.82 -12.7 30-60 50.53 48.43 47.12 46.82 -7.3 60-90 42.66 47.23 45.67 48.56 13.8
90-120 37.55 41.55 38.77 43.98 17.1 120-150 38.55 44.52 41.26 46.91 21.7
Gypsum @ GR 100% (T1)
0-15 54.32 47.51 52.28 47.39 -19.1 16-30 60.31 49.86 56.55 52.47 -14.4 30-60 53.56 52.14 50.22 47.26 -11.8 60-90 41.55 47.16 46.07 48.36 16.4
90-120 34.22 37.95 36.28 39.55 15.6 120-150 38.26 41.98 40.27 42.55 11.2
FYM 20 Mg ha-1
(T2)
0-15 63.21 62.45 54.55 50.73 -22.9 16-30 47.22 45.95 43.32 37.14 -21.3 30-60 45.83 43.26 41.56 40.05 -12.6 60-90 33.51 37.95 36.85 39.24 17.1
90-120 38.22 40.55 39.67 42.39 10.9 120-150 32.94 36.52 33.55 37.55 14.0
Gypsum @
GR50%+FYM 10 Mg ha-1
(T3)
0-15 67.51 61.38 62.32 50.44 -25.3 16-30 55.77 50.83 43.67 40.83 -26.8 30-60 53.29 54.86 47.24 46.28 -13.2 60-90 40.32 47.11 45.09 48.36 19.9
90-120 41.29 42.66 40.97 44.36 7.4 120-150 41.39 44.97 43.02 46.88 13.3
Gypsum @ GR 100% +FYM 10 Mg ha-1
(T4)
0-15 53.21 50.64 37.63 35.62 -33.1 16-30 66.31 55.55 49.33 43.58 -34.3 30-60 56.23 53.56 49.24 47.55 -15.4 60-90 46.03 48.38 47.25 49.35 7.2
90-120 35.78 39.98 38.05 41.01 14.6 120-150 43.26 41.95 45.29 43.01 -0.6
Pure Tree Plantation
(Acacia nilotica)
0-15 60.31 49.82 56.01 53.41 -11.4 16-30 63.22 62.41 54.02 55.42 -12.3 30-60 61.33 58.43 57.74 55.29 -9.8 60-90 61.82 65.29 63.15 67.21 8.7
90-120 52.87 57.02 55.39 58.42 10.5 120-150 40.26 45.71 43.26 46.01 14.3
152
Table 4.39 Effect of amendments on soil sodium adsorption ratio (SAR) Eucalyptus-
based agroforestry systems
Treatment Depth
(cm)
Eucalyptus-based agroforestry systems
May
2011
Nov
2011
May
2012
Nov
2012
% change over
initial value
Control (To)
0-15 57.33 54.51 50.53 48.72 -15.0 16-30 67.11 64.52 60.48 58.71 -12.5 30-60 64.49 62.56 61.39 59.28 -8.1 60-90 56.34 58.41 57.39 60.67 7.7 90-120 54.12 57.08 55.37 58.54 8.2
120-150 51.81 56.82 54.21 57.39 10.8
Gypsum @ GR 100% (T1)
0-15 55.81 51.67 49.12 47.23 -15.4 16-30 67.63 65.23 62.54 58.31 -13.8 30-60 65.38 68.25 63.56 60.23 -7.9 60-90 57.36 63.28 60.55 64.24 12.0 90-120 53.55 57.22 55.26 58.36 9.0
120-150 58.37 64.53 61.82 65.15 11.6
FYM 20 Mg ha-1
(T2)
0-15 54.55 50.43 47.36 43.26 -20.7 16-30 64.25 60.72 56.71 54.13 -15.8 30-60 63.28 61.07 58.23 57.22 -9.6 60-90 51.84 55.28 53.88 56.18 8.4 90-120 62.91 66.22 64.52 67.15 6.7
120-150 57.36 62.51 60.22 63.55 10.8
Gypsum @ GR50%+FYM
10 Mg ha-1
(T3)
0-15 56.52 52.73 48.62 45.71 -19.1 16-30 66.39 63.71 59.62 55.78 -16.0 30-60 67.39 64.34 65.41 61.24 -9.1 60-90 62.33 68.33 65.46 70.37 12.9 90-120 58.71 61.38 60.81 63.16 7.6
120-150 57.43 62.57 60.11 65.12 13.4
Gypsum @ GR
100% +FYM 10 Mg ha-1
(T4)
0-15 62.32 56.54 52.66 48.56 -22.1 16-30 64.95 61.31 58.66 55.37 -14.7 30-60 62.09 59.24 57.46 54.28 -12.6 60-90 53.12 58.37 56.58 59.55 12.1 90-120 57.33 61.37 59.66 62.34 8.7
120-150 54.31 58.24 57.36 59.36 9.3
Pure Tree Plantation (Eucalyptus
camaldulensis)
0-15 60.31 58.05 58.34 57.37 -4.9 16-30 64.37 61.37 58.37 57.87 -10.1 30-60 66.03 63.54 59.42 56.23 -14.8 60-90 63.84 66.45 64.95 67.15 5.2 90-120 55.91 57.95 57.02 59.38 6.2
120-150 54.89 56.22 55.34 57.72 5.2
153
4.2.5 Discussion
The results described in the preceding section are discussed in the light of literature
collected for comparison and clarifications.
4.2.5.1 Para grass growth and production under sole cropping and alley cropping
systems
Results of our studies presented in tables 4.23 to 4.27 showed that growth of para
grass grown in sole cropping (open field) and in agroforestry systems (Acacia-based and
Eucalyptus-based) was affected with application of gypsum and farm yard manure (applied
solely or jointly with different formulations). In general, growth of para grass responded
positively to application of amendments. Combined dose of gypsum and farm yard manure
further enhanced biomass production as compared to control and other treatments where
amendments were applied solely.
The lowest level of recorded parameters was observed in control (no amendment);
whereas highest level was achieved in treatment plots applied with higher level of
amendment (Gypsum @ GR 100% +FYM 10 Mg ha-1). The greater availability of organic
carbon in the form of farm yard manure (Blair et al., 2006; Sullivan et al., 2007) and
reclaiming effect of gypsum improved biomass production as compared to control plots (no
amendment).
In sole cropping system (open field), stolon height, culm length, number of tillers per
plant of para grass increased gradually with the enhancement of soil fertility status with
application of soil amendments. The increased accessibility of nutrient (Ortega et al., 2002;
Blair et al., 2006), improvement of soil water holding capacity in treated plots incorporated
with FYM and gypsum might be the possible reasons for improved biomass production. The
improved grass stand might also be due to the softness of soil caused by manure in which the
roots may expand rapidly to meet plant water requirements. Increased availability of
optimum amount of soil water and organic carbon from farm yard manure (Dolan et al.,
2006) resulted in increased cell division, expansion and enlargement and ultimately
production of taller plants.
154
Results showed that application of fertilizer and/or farm yard manure improved the
tillering potential, hence higher number of tillers per plant showed that plots applied with
amendments had better growth as compared to control. Similarly, Badaruddin et al. (1999)
and Hossain et al. (2002) have also reported significant increase in tillers m-2 in experimental
plots applied with organic and inorganic fertilizers. Higher fresh and dry matter yield of para
grass was observed in plots amended with gypsum and farm yard manure as compared to
control (no amendment).
4.2.5.2 Tree growth and wood production under sole plantation and afgroforestry based
systems
Results of present studies (Tables 4.28 and 4.29) showed that tree growth and wood
production of A. nilotica and E. camaldulensis grown in sole plantation and in agroforestry
systems (Acacia-based and Eucalyptus-based) were affected by the application of gypsum
and farm yard manure (applied solely or jointly with different formulations). Mean annual
increment (MAI) of both the tree species (A. nilotica and E. camaldulensis) in their sole and
in agroforestry systems was monitored for two consecutive years of experimentation. Growth
rate of trees intercropped with para grass was affected positively with the application of
different soil amendments as compared to control (no amendment) and sole tree plantation.
The lowest level of MAI was observed in control plots (no amendment); whereas the highest
level of MAI was attained in treatment plots applied with Gypsum @ GR 100% +FYM 10
Mg ha-1.
Better growth rate of trees observed in agroforestry systems may be attributed to the
application of amendments in experimental plots. Thus, the trees seem to be benefitted by
exploiting nutrient availability due to application of farm yard manure amendments. Use of
organic fertilizers and ameliorative effect of farm yard manure in agroforestry systems
provided pleasant soil environment for optimum soil microbial activity, which in turn, might
have caused rapid mineralization of organic matter thus facilitating the uptake of nutrients by
trees. Beneficial effects of growing understorey vegetation in association with tree
plantations have also been reported by several researchers under different soil and climatic
conditions (Sharma and Singh, 1992; Singh et al., 1997).
155
Results of the present study are in line with findings of Szott and Kass (1993) who
concluded that fertilizer response was positive on tree growth in alley cropping systems.
Ahmed (1991) has also reported that growth of A. nilotica and Eucalyptus improved in saline
environment when these plants were applied with soil amendments as gypsum and farm yard
manure. These results are in agreement with the findings of Gupta (1991) and Datta and
Singh (2007) regarding the enhanced yield component of wood production on degraded land;
it was due to better soil conditions having reclamation actions and the soil regeneration
potential of trees on degraded land.
4.2.5.3 Biomass productivity under different systems
The biomass productivity status in any ecosystem is governed by prevailing climatic
conditions and edaphic characteristics. The increased availability of nutrients in the soil due
to application of amendments (gypsum and/or farm yard manure) might be the possible
reason for increased biomass production in agroforestry systems. Moreover, in case of
compatible agroforestry systems, total productivity of the systems is increased due to several
factors like higher resistance to recurrent ecological alterations, increased availability of vital
nutrients and healthy effect of root exudates in rhizospheres, enhanced consumption and
reutilization of resources as stated by Liebman and Gallandt (1997).
In intercropping systems, yield of component intercrops may be reduced but total
yield of intercrops can be significantly greater than that of each crop in a monoculture if
proper system of intercropping is used. In present studies, biomass production gradually
increased in alley cropping systems by the application of suitable amendments. There was
more compatibility in Acacia-para grass based system as compared to Eucalyptus-para grass
based system as the former supported higher growth of understorey para grass. Application
of treatment (Gypsum @ GR 100% + FYM 10 Mg ha-1) to experimental plots supported
higher biomass production of para grass in all the systems (open field, Acacia-based and
Eucalyptus-based systems). Our results are in agreement with the findings of other
researchers like Dhyani and Tripathi (1999), Bhatt et al. (2005) and Datta and Singh (2007).
156
4.2.5.4 Soil properties variation in different cropping systems with application of
amendments
4.2.5.4.1 pH
In open field conditions, soil pH increased within upper soil depth (0-15 cm) with
growing of para grass for two years in control treatment (no amendment). This increase may
be attributed to the continuous application of brackish irrigations water (high SAR and RSC)
to wheat crop during both the seasons. However, application of farm yard manure alone or
blended with gypsum resulted in reduction of soil pH in soil profile at various depths. The
decrease in pH may be outcome of application of farm yard manure which had ameliorative
effect on soil pH during both the growth seasons.
In Acacia-based and Eucalyptus-based alley cropping systems, tree plantation
improved soil pH to varying levels in control as well as with application of amendments. In
present studies, more pH reduction was observed in Acacia-based systems as compared to
Eucalyptus-based system. Similar trend was followed in their sole plantations as A. nilotica
plantation was found to have more restorative and ameliorative effect as compared to E.
camaldulensis. Possible reason for higher ameliorative effect may be due to higher leaf litter
fall in A. nilotica as compared to E. camaldulensis and plasticity effect of leaves of E.
camaldulensis. Application of organic amendment (farm yard manure especially blended
with gypsum) has enhanced ameliorative effect on soil pH at various depths in soil profile.
The primary factor responsible for reduction of soil pH may be reduced
evapotranspiration, better water holding capacity of soil, fall of leaf litter and higher
microbial activities in improved microclimate prevailing in alley cropping systems as
compared to open field conditions. Higher plant biodiversity in the alley cropping systems
leads to higher respiration of CO2 (Robbins, 1986) which reacts with water to make H2CO3
which upon dissociation releases H+. The proton thus released is primary force responsible
for reduction in soil pH (Qadir et al., 2005). Litter component of tree is a measure of the net
H+ release and hence reduction in soil pH. Our results are in conformity with the findings of
Singh et al. (1995) and Basavaraja et al. (2011).
157
4.2.5.4.2 Soil electrical conductivity
Electrical conductivity (EC) is a measure of soluble salts present in soil-water system.
Results of our studies conducted in open field condition showed that soil EC increased in
upper soil layer (depth 0-15 cm) with growing of para grass for successive two years in
control (no amendment) condition. The increase may be attributed to continuous irrigations
with brackish water used for irrigation of the para grass during both the cropping seasons.
However, application of farm yard manure in blended form with gypsum resulted in
reduction of soil EC in soil profile. The decrease in soil EC may be outcome of application of
farm yard manure which had ameliorative effect during both seasons.
In Acacia-based and Eucalyptus-based alley cropping systems, soil electrical
conductivity decreased at varying level in control plots as well as in plots applied with
amendments. In present studies, more soil electrical conductivity reduction was observed in
Acacia based systems as compared to Eucalyptus based ones. Similar trend was followed in
their sole plantations as A. nilotica plantation was found to be more restorative and
ameliorative as compared to E. camaldulensis. Overall, the leaching of soluble salts from the
root zone to the lower soil depths with irrigation and/or rain water remained the main cause
for decreasing electrical conductivity of soil. Leaching of salts is facilitated by the roots of
trees/vegetation by providing channels for water and solute movement to the lower soil
profile (Qadir et al., 2003).
Application of farm yard manure alone or blended with gypsum has enhanced
ameliorative effect on soil EC at various depths in soil profile. Addition of organic matter by
tree plantation is reported to increase porosity of soil (Grag, 1998). In tree farming systems,
roots in soil profile decay oftenly and this phenomenon leads to conversion of soil pores into
macropores (Yunusa et al., 2002; Devine et al., 2002), which increases infilteration rate and
facilitates leaching of salts. Addition of organic amendments improves soil structure and
increases porosity. Such positive development in alley cropping systems leads to enhanced
reduction in soil EC.
158
4.2.5.4.3 Soil sodium adsorption ratio
Soduim adsorption ratio (SAR) is the measure of sodicity present in soil-water
system. Results of our studies conducted in open field condition showed that soil SAR
increased in upper soil layer (depth 0-15 cm) after growing of para grass for successive two
years in control (no amendment) condition. The increase may be attributed to continuous
irrigations with high SAR and RSC water as brackish water was used for irrigation of the
para grass during both cropping seasons. However, application of farm yard manure in
blended form with gypsum resulted in reduction of soil SAR in the profile. The decrease in
soil SAR with farm yard manure appears most probably through Ca2+ released from soil lime
as a result of CO2 released during FYM biochemical oxidation.
In Acacia and Eucalyptus-based alley cropping systems, soil SAR decreased at
varying levels in control as well as in treatments where application of amendments was
made. In present studies, more soil SAR reduction was observed in Acacia-based systems as
compared to Eucalyptus-based ones. Similar trend was observed in their sole plantations as
A. nilotica plantation was found to be more restorative and ameliorative as compared to E.
camaldulensis. Overall, leaching of soluble salts from root zone to the lower soil depths with
irrigation and/or rain water remained the main cause for decreasing sodium adsorption ratio
of soil. Leaching of salts is facilitated by the roots of trees/vegetation by providing channels
for water and solute movement to lower soil profile (Qadir et al., 2003).
Application of farm yard manure alone or blended with gypsum has enhanced
ameliorative effect on soil SAR at various depths in the soil profile. Addition of organic
matter by tree plantation is reported to increase porosity of soil (Grag, 1998). Addition of
organic amendments improved soil structure and increased the soil porosity. Such positive
signs in alley cropping systems lead to enhanced reduction in soil SAR.
159
Chapter 5
SUMMARY
Agroforestry systems offer magnificent potential to preserve or upsurge farm
productivity round the globe. Biomass productivity of agroforestry systems which is mainly
dependent on interaction of growth limiting factors, may get undesirably upset on account of
intensified competition in semi-arid regions. It is, therefore, imperative to develop
appropriate alley cropping systems comprising of trees and understorey components
(crops/grasses) with multi-dimensional complementarity, and applied with suitable soil
amendments (as nutrient source) to prevaricate losses in biomass productivity/harvestable
product(s)/crop yield(s).
The objectives of present research work were to evaluate effect of application of
inorganic and organic amendments on biomass productivity and salt dynamics in soil profile
in different agroforestry systems. The experiments were carried out at Biosaline Research
Station (BSRS), Pakka Anna, Nuclear Institute for Agriculture and Biology, Faisalabad,
Pakistan. Agroforestry systems included Acacia-based and Eucalyptus-based systems
intercropped with wheat and para grass. Upper and understorey components of
aforementioned systems were also evaluated in sole systems for comparison of productivity
of different systems.
In Acacia and Eucalyptus-wheat based systems, treatments included nitrogen (60, 120
kg N ha-1) and farmyard manure (10, 20 Mg ha-1) which were applied alone and in combined
form with different formulations. Similarly, in case of Acacia and Eucalyptus-para grass
based systems, treatments included gypsum (@ GR 50 and 100%) and farmyard manure (10,
20 Mg ha-1) which were applied alone and in combined form with different formulations.
Experiments were carried out in RCBD with split plot arrangement having four replications.
Salient conclusions drawn from experimental results are summarized as:
160
Study 1: Acacia- and Eucalyptus-wheat based alley cropping systems
Higher trend in growth and yield parameters of wheat was observed in open field
system (full sunlight); whereas it was lower in Acacia-based systems and lowest in
Eucalyptus-based system.
Experimental plots applied with treatment (FYM 20 Mg + N 60 kg ha-1) supported
the highest biomass production of wheat in all the systems (open field, Acacia and
Eucalyptus based systems) as compared to other experimental treatments.
Higher compatibility was observed in Acacia-wheat based system as compared to
Eucalyptus-wheat based system as the former system supported higher growth of
understorey wheat crop.
In open field conditions, the lowest biomass productivity of 4302 kg-1 ha-1 yr-1 was
achieved in wheat grown in open field, whereas the highest biomass (7956 kg-1 ha-1
yr-1) was obtained in treatment applied with FYM-20 Mg +N 60 kg ha-1.
In Acacia-wheat agroforestry systems, the lowest biomass (tree + wheat) productivity
of 5586 kg-1 ha-1 yr-1 was gained in control plots (no amendment) whereas; the
highest biomass (8919 kg-1 ha-1 yr-1) was recorded in treatment where FYM-20 Mg
+N 60 kg ha-1 was applied. In sole plantations of A. nilotica, biomass productivity
was 1853 kg-1 ha-1 yr-1.
In Eucalyptus-wheat agroforestry systems, the lowest biomass (tree + wheat)
productivity (6764 kg-1 ha-1 yr-1) was achieved in wheat control plots (no amendment)
grown in open field whereas; the highest biomass (10084 kg-1 ha-1 yr-1) was obtained
in plots applied with (FYM-20 Mg +N 60 kg ha-1). In sole plantations of E.
camaldulensis, biomass productivity was 3752 kg-1 ha-1 yr-1.
Soil properties pH, electrical conductivity and sodium adsorption ratio improved
more in Acacia based systems than other ones. Use of amendments further enhanced
soil restoration process with the highest improvement in soil properties with
application of (FYM-20 Mg +N 60 kg ha-1).
161
Study 2: Acacia- and Eucalyptus-para grass based alley cropping systems
Higher trend in growth and production of para grass was observed in open field
system (full sunlight); whereas it was lower in Acacia-based system and lowest in
Eucalyptus-based system.
Application of gypsum and farm yard manure treatment (Gypsum GR 100% +FYM
10 Mg ha-1) supported higher biomass production of para grass in all the systems
(open field, Acacia and Eucalyptus based systems).
Higher compatibility was observed in Acacia-para grass system than Eucalyptus-para
grass system as the former supported higher growth of understorey para grass.
In open field conditions, annual biomass productivity of para grass was 7940 kg ha-1
yr-1 in control plots (no amendment) and 12800 kg ha-1 yr-1 in plots applied with
treatment (Gypsum @GR 100% + FYM 10 Mg ha-1).
In Acacia-based agroforestry system, the lowest annual biomass (tree + para grass)
productivity was 8436 kg ha-1 yr-1 in plots applied with no amendment (control)
which increased to 14344 kg ha-1 yr-1 due to application of gypsum and farm yard
manure. In case of sole plantation of A. nilotica, total biomass productivity was 1521
kg ha-1 yr-1.
Eucalyptus-based agroforestry system had the lowest annual biomass productivity
(8615 kg ha-1 yr-1) in control conditions whereas, with amendments (Gypsum @GR
100% + FYM 10 Mg ha-1), biomass productivity increased to14664 kg ha-1 yr-1.
Soil properties pH, electrical conductivity and sodium adsorption ratio improved
more in Acacia based systems than other ones. Use of amendments (gypsum and/or
farm yard manure) further enhanced soil amelioration process.
162
Concluding remarks and recommendations
The results presented in this thesis suggest development of compatible agroforestry
systems for salt-affected soils as agroforestry systems are more productive than sole cropping
systems. In present studies, it was observed that Acacia-based systems are more compatible
for understrorey components i.e., wheat and para grass. However, overall total productivity
of Eucalyptus-based systems is higher than Acacia-based systems due to higher growth rate
of woody component (E. camaldulensis). Acacia-based systems are more ameliorative as
compared to Eucalyptus-based systems. Hence, in order to fetch higher biomass productivity
from salt-affected soils, Acacia-based systems may be promoted for getting higher
production of understorey components. Application of suitable amendments especially farm
yard manure and gypsum may further enhance biomass productivity of agroforestry systems
as well as restoration process of salt-affected soils. Further trials on such lines are
recommended on farmers’ field to verify the beneficial results of present studies.
In essence, agroforestry systems are more productive and environment friendly as
compared to monoculture systems. Therefore, concerted efforts are required by the stake
holders for the adoption of agroforestry systems by farming communities to harness the
benefits of agroforestry in saline environment as well as normal cropping systems.
163
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