evaluation of micronutrient status of soils under three ... · evaluation of micronutrient status...

32 Onwudike et al., Evaluation of micronutrient status…

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Volume-2, Issue-1, pp- 32 - 40

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Research Paper July 2016

Evaluation of Micronutrient Status of Soils under Three Land Use

Types in Oyigbo, River State, Nigeria

Onwudike, S. U1, Onweremadu, E. U

1, Ihem, E. E

1, Agim, L.C

1, Osisi, A. F

1,Osuaku, S. K

2

and Azuh, P. O1.

1Department of Soil Science and Technology, Federal University of Technology Owerri, Imo State Nigeria

2Department of Agricultural Science, Alvan Ikoku Federal College of Education Owerri, Imo State Nigeria

Corresponding author: Onwudike Stanley Uchenna, Department of Soil Science and Technology,

Federal University of Technology Owerri Imo State Nigeria.

onwudikestanley@yahoo.com

Abstract

This investigation was carried out to evaluate status of micronutrients of soils as influenced by land use

types in Oyigbo, River State. Three land use types namely forested land, cassava dominated farm land and

maize dominated farm land in four villages in Oyigbo were studied with soil samples collected from 0 – 30

cm depth in each land use. The soils were air dried, sieved and subjected to routine laboratory analysis

using standard methods. Data obtained were subjected to analysis of variance (ANOVA) and significant

treatment means were separated using Least Significant Difference (LSD) at 0.05 probability level.

Relationship between soil micronutrients and selected soil physicochemical properties were determined

using correlation analysis. Results showed that the textures of the studied soils were not affected by land use

practices. The lowest value of soil bulk density and highest values of total porosity and gravimetric moisture

content were recorded in forested land. Soil pH, organic carbon, total nitrogen and available phosphorus

were higher in forested land with the sequence forested land > cassava dominated farm land > maize

dominated farm land. Similarly, forested land recorded the highest concentrations of Mn (3.13 mg/kg), Zn

(1.58 mg/kg) and Bo (0.78 mg/kg) in this sequence forested land > cassava dominated farm land> maize

dominated farm land. Therefore, proper agronomic practices that will increase soil pH and organic matter

in the area should be practiced when lands are put into cultivation. Farmers should be encouraged to

embrace organic manuring and minimum tillage.

Keywords: land use, micronutrient, nutrient depletion, soil fertility

1.0 Introduction

Soil plays a vital role in determining the sustainable productivity of an agro-ecosystem. Sustainable

productivity of soils depends upon its ability to supply essential nutrients to the growing plants. Field trials

have shown that the deficiency of micronutrients in soils has become a major constraint to the productivity

and sustainability of soil (Jiang et al., 2009). Large hectares of arable land in Nigeria have been reported to

be deficient in both macro and micronutrients and these deficiencies were brought about by factors such as

continuous use of inorganic fertilizers particularly nitrogen, phosphorus, and potassium by farmers, limited

use of organic manures as well as non-recycling of crop residues (Ibrahim et al., 2011). Several authors have

indicated that the availability of micronutrients in soils depends on soil pH, organic matter content,

33 Onwudike et al., Evaluation of micronutrient status…

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adsorptive surfaces and other physical, chemical and biological conditions in the rhizosphere (Kabata-

Pendias, 2001, Yadav, 2011).

In trying to meet up with the food demand for teeming human population as well as need for raw

materials for industrial purposes in Nigeria, agricultural lands are subjected to different land uses and

anthropogenic activities such as deforestation, over grazing and improper agricultural practice (Onwudike et

al., 2015). Others are plantation farm and continuous cultivation of arable lands. These activities change soil

physicochemical properties including soil micronutrients over time (Bonuma & Progers, 1998) as a result of

top soil removal by erosion (FAO, 1998), soil acidification and organic matter depletion (IFPRI, 2010).

Evaluation of micronutrient status of soils has become very vital in making policies and

recommendations for sustainable agricultural development. Oyigbo in River State, Nigeria is a tropical

region where lands are put into different uses especially for agricultural purposes and unfortunately, these

agricultural lands are not often evaluated to determine the status of micronutrients in the soil. Therefore, the

objective of this work was to evaluate the micronutrient status of soils under three land use types in the

region. Specifically, the work was aimed at evaluating the physicochemical properties, selected

micronutrients in the studied location as well as determining the relationship between micronutrients and

selected physico-chemical properties.

2.0. Materials and Methods

2.1. The Study Area

The study was conducted at Oyigbo Local Government Area of River State. The area lies on latitudes 4° 52'

N and longitudes 7° 42' E. The area has a lowland geomorphology of below 52 m above sea level. It is

rainforest vegetation with mean annual rainfall of 2,000 – 2,500 mm and mean temperature range of 26 °C –

28 °C. The area has two distinct seasons: rainy season (April – October) and dry season (November –

March). The rainy season has a bimodal distribution pattern with distinct peaks in July and September.

There is usually dry spell between this peaks in August (August break), but due to changes in the weather

condition as result of climate change, there has been inconsistency in the occurrence of the dry spell. The

soils are rich sources of mineral deposits such as crude oil. Farming is the major socio-economic activity of

people in the area while soil fertility restoration in the region is through inorganic and organic fertilization.

2.2. Field Study

Three land use types namely cassava dominated farm land, maize dominated farm land and forested land

were studied in four communities in Oyigbo Local Government Area. These communities were

Umuebereke, Egbelukwu, Nmirinyayi and Umuagbai. In each land use type, four soil samples were

randomly collected from the four villages at the depths of 0 – 30 cm. The four sampling points acted as

replications. Soil samples collected were air dried at room temperature, sieved with 2 mm sieve and

subjected to laboratory analysis using standard methods.

2.3. Laboratory Analysis

Determination of particle size distribution was by hydrometer method (Gee & Or, 2002) using Sodium

hexametaphosphate (Calgon) as dispersant. Bulk density was estimated using core method and calculated as

mass of oven dried soil divided by volume of core sampler (Foth, 1984). Soil moisture content was

determined gravimetrically. Total porosity of the soil was calculated from bulk density assuming a particle

density of 2.65 mg m-3

with the following formula according to Foth, (1984):

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Total porosity (TP) = 1 – {(Bulk density/particle density)} x 100 (1)

Soil pH was determined electrometrically in a 1: 2.5 soil: solution ratio (Hendershotet al., 1993). Organic

carbon was determined by wet oxidation method (Nelson & Sommers, 1982). Total Nitrogen was

determined using the modified micro-kjeldahl method (Bremner & Mulvaney, 1982). Available phosphorus

was determined by extraction with Bray II solution and determined calorimetrically on spectrophotometer

according to Olsen & Sommers (1982). Exchangeable bases were determined using 1N ammonium acetate

solution according to Jackson (1964). Exchangeable Calcium (Ca) and Magnesium (Mg) was determined

using ethylene diaminetetracetic acid (EDTA) while exchangeable Potassium (K) and Sodium (Na) were

determined flame photometrically. Exchangeable acidity (Al3+

& H+) was determined according to Mclean

(1982). Effective Cation Exchange Capacity (ECEC) was computed by the summation of all exchangeable

bases and exchangeable acidity while percentage base saturation was calculated by dividing total

exchangeable bases with effective cation exchangeable capacity and the quotient multiplied by 100.

The soil was extracted with 0.005 M DTPA for available micronutrients (Bo, Zn, and Mn) according

to Lindsay et al., (1978) and the micronutrients were determined using atomic absorption spectrometer. Data

obtained were subjected to Analysis of Variance (ANOVA) while relationships between soil properties and

micronutrients were determined using linear correlation

3.0. Results and Discussion

3.1. The Physical Properties of The Studied Locations

The physical properties of soils in the studied locations are presented in Table 1. Results showed that soils

were mainly dominated by sandy loam with high sand fraction in the three land use types. There was no

significant effect on the particle size distribution of the soil irrespective of land use type. This observation

contradicted the observation of( Agoumé & Birang 2009) that reported a significant effect on the clay, silt

and sand fractions of the soil and attributed the differences to variations in climatic condition. However, this

result agrees with the findings of Shepherd et al. (2000) who observed no effect on soil particle size

distribution under different land use systems. The high sand fraction in the studied locations could be

attributed to the parent material dominant in the area which is coastal plain sand (Benin formation) since the

texture of the soil is highly influenced by the parent material over time (Oguike & Mbagwu, 2009).

Also, the humid rainfall characteristics that promote illuviation or leaching of silt and clay

particles below the epipedon could contribute to the texture of soils in the area. Forested land recorded the

lowest soil bulk density (1.62 mg/m3), followed by cassava dominated farm land and the highest was maize

dominated farm land (1.97 mg/m3). The high bulk density recorded in maize dominated farm land could be

attributed to frequent tillage activities since maize is an annual crop unlike cassava (biennial) and forested

land. This is because tillage activities could reduce organic matter accumulation which reduces soil bulk

density. Therefore litter falls in the forested land which after decomposition, increases aggregation and

microbial activities could contribute to lower bulk densities in fallow. Soil total porosity ranged from 22.8 –

35.6 % with the highest in the forested land (36.6 %) and the lowest in maize cultivated land (22.8 %).

Increase in soil bulk density resulted to a decrease in soil total porosity which could be attributed to

compaction of soil macro and micro pore spaces. Forested land recorded the highest soil moisture content of

139 g/kg while the lowest value was in cassava cultivated land (116 g/kg). High moisture content in the

fallow land could be as a result of high biomass turn over and high organic matter accumulation which

retains soil moisture and enhances water infiltration due to microbial activities (Oguike & Mbagwu, 2009).

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Table 1: Soil Physical Properties of the Studied Locations

Location Land use Sand Silt Clay Textural BD TP MC

g/kg g/kg g/kg Class mg/m3 % g/kg

Umuagbai Cassava 742.4 52.8 204.8 Sandy loam 1.86 27.3 123

Umueberelle Cassava 732.4 42.8 204.8 Sandy loam 1.88 26.6 125

Mmirinyayi Cassava 762.4 72.8 164.8 Sandy loam 1.70 33.6 108

Egbelukwu Cassava 762.4 52.8 184.8 Sandy loam 1.78 30.5 109

Mean 749.9 55.3 189.8 Sandy loam 1.81 29.5 116

Umuagbai Maize 722.4 52.8 224.8 Sandy loam 1.93 24.6 130

Umueberelle Maize 832.4 82.8 84.8 Sandy 2.0 21.9 132

Mmirinyayi Maize 852.4 52.8 72.8 Sandy 2.07 19.1 134

Egbelukwu Maize 712.4 72.8 214.8 Sandy loam 1.91 25.4 129

Mean 779.9 65.3 149.3 Sandy loam 1.97 22.8 131

Umuagbai Forested 812.4 52.8 134.8 Sandy loam 1.54 34.8 116

Umueberelle Forested 762.4 12.8 224.8 Sandy loam 1.58 38.3 156

Mmirinyayi Forested 782.4 12.8 204.8 Sandy loam 1.63 36.3 169

Egbelukwu Forested 802.4 62.8 134.8 Sandy loam 1.72 32.8 115

Mean 789.9 35.3 174.8 Sandy loam 1.62 35.6 139

LSD(0.05)

NS NS NS

0.16 5.92 69.9

NS = Not significant at 0.05 probability level, TC: textural class, BD: bulk density, MC: moisture content,

3.2. The Chemical Properties of Soils

The chemical properties of the studied locations are shown in Table 2. Results showed that the soils were

moderately acidic with forested land recording the highest soil pH in water (5.50) while cassava dominated

farm land recorded the lowest pH (5.13). High soil pH in forested land could be attributed to litter falls

which after decomposition increases soil organic matter and exchangeable bases thereby reducing the

accumulation of H and Al ions on soil exchange complex as stated by Onwudike, (2010). Lower values of

soil pH in Cassava dominated farm and maize dominated farm lands could be due to continuous cultivation

of soil which increases water infiltration, run off and leaching of basic cations with resultant accumulation of

H+

and Al3+

on the exchange complex. Comparing the three land uses, forested land recorded highest values

of organic carbon (2.81g/kg), soil total nitrogen (0.38 g/kg) and available phosphorus (9.43 mg/kg). High

organic carbon in the forested land could be due to litter fall and expected increase in soil biodiversity

(Miller & Grardiner, 2001). (Woldeamlak & Stroosnijder 2003) have observed that conversion of forest

vegetation to agricultural land results to a decline in soil organic carbon content. High total nitrogen and

available phosphorus recorded in forested land could be due to higher soil organisms that help in organic

matter decomposition since there is a positive correlation between organic matter and total nitrogen.

Forested land recorded the highest values of exchangeable bases when compared to maize and cassava

dominated farm lands. Low exchangeable bases in these locations could be due to high rainfall which

accelerates runoff and leaching of cation down the subsoil. Higher exchangeable bases in the forested land

could be due to the macro and micro - climate that hinders the impact of rain drops on soil (Chen & Xu,

2010). Low values of soil organic carbon in cassava and maize dominated farm lands could be attributed to

the rapid decomposition and mineralization of soil organic matter due to nutrient uptake by plants. Similar

findings were reported by (Agoumé & Birang 2009) who recorded the lowest soil organic carbon on crop

land as compared to forested land.

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Table 2: Soil Chemical Properties of the Studied Location

ECEC: Effective cation exchange capacity, TEA: Total exchangeable bases, BS: base saturation

3.3. Distribution of Micronutrients

The status of micronutrients in the land use types are presented in Figure 1. Results showed that among the

three land uses there was higher concentration of boron (Bo), zinc (Zn) and manganese (Mn) in the forested

land than in cassava and maize dominated farm lands. Forested land had 3.13 mg/kg of Mn, 1.58 mg/kg of

Zn and 0.78 mg/kg of Bo. The sequence of micronutrient concentration was forested land > maize

dominated farm land > cassava dominated farm land. The concentrations of these micronutrients are below

the critical limit for their deficiencies in soil except Zn as stated by Yadav (2011).

High availability of these micronutrients in forested land could be attributed to high soil pH in the

forested land since according to Yadav (2011), soil pH is an important soil factor controlling micronutrient

availability. Similarly, at high pH, divalent forms of some micronutrients like Mn could be oxidized to

trivalent and tetravalent forms which are insoluble in water and hence unavailable to plants thereby

increasing their concentration in soil (Samasundaram et al., 2009). In forested land, high soil organic matter

and biodiversity due to less soil disturbance could contribute to high Zn and Mn concentration; hence, the

need for sustainable management intervention in cassava or maize dominated farm lands. This observation is

in concord with Samasundaram et al., (2009) who stated that soil organic matter increases soil

micronutrients due to the chelating property of soil organic matter in holding soil micronutrients.

Location Land use

pH

(H20)

pH

(KCl)

Organic

Carbon

Total

N

Avail.

P Ca Mg

Exch.

K Na TEA ECEC BS

g/kg g/kg mg/kg

cmol/kg

%

Umuagbai Cassava 5.08 4.88 2.23 0.45 10.51 0.90 0.19 0.33 0.09 2.00 3.31 39.70

Umueberelle Cassava 5.10 4.92 1.19 0.48 10.62 0.50 0.17 0.33 0.09 2.60 4.68 44.50

Mmirinyayi Cassava 5.20 5.00 0.32 0.03 5.33 1.28 0.80 0.33 0.02 1.92 4.34 55.80

Egbelukwu Cassava 5.12 4.98 0.28 0.02 5.42 1.33 0.20 0.33 0.02 2.52 4.40 42.80

Mean 5.13 4.95 1.00 0.25 7.97 1.00 0.34 0.33 0.05 2.26 4.18 45.70

Umuagbai Maize 5.43 5.16 2.59 0.22 7.83 1.20 0.17 0.24 0.02 1.40 3.03 53.80

Umueberelle Maize 5.42 5.10 1.69 0.40 10.21 2.99 0.90 0.24 0.03 1.42 5.57 74.50

Mmirinyayi Maize 5.48 5.13 2.79 0.41 9.96 3.17 0.50 0.24 0.03 1.44 5.37 73.20

Egbelukwu Maize 5.46 5.62 2.47 0.21 8.93 1.26 0.20 0.22 0.02 1.10 2.80 66.80

Mean 5.45 5.25 2.38 0.31 9.23 2.16 0.44 0.24 0.02 1.34 4.19 67.08

Umuagbai Forested 5.62 5.20 2.61 0.15 6.48 1.17 0.50 0.25 0.09 1.24 3.25 61.90

Umueberelle Forested 5.29 4.96 2.98 0.60 12.03 1.52 0.31 0.34 0.09 1.40 3.65 61.70

Mmirinyayi Forested 5.26 4.92 2.87 0.51 10.52 1.50 0.29 0.33 0.07 1.20 4.19 71.40

Egbelukwu Forested 5.82 5.05 2.76 0.25 8.69 1.43 0.58 0.26 0.09 1.16 3.52 67.00

Mean 5.50 5.03 2.81 0.38 9.43 1.41 0.42 0.29 0.09 1.25 3.65 65.50

LSD(0.05)

0.19 0.17 0.42 0.35 3.81 1.14 0.54 0.04 0.04 0.40 1.27 8.38

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Figure 1: Distribution of micronutrients in the studied land use types.

3.4. Relationship between Soil Micronutrients and Selected Soil Properties

The relationship between Bo, Zn and Mn with selected soil properties are shown in Table 5. Results showed

that significant positive correlations existed between soil pH and Bo (r = 0.7021), Zn (r = 0.5584) and Mn (r

= 0.6424) while bulk density significantly correlated negatively with Bo (r = - 0.6746), Zn (r = - 0.5356) and

Mn (r = - 0.7008). There was significant positive correlation between ECEC and organic carbon (r =

0.6127), Zn and organic carbon (r = 0.8797), organic carbon and Mn (r = 0.6170). Similar relationship

existed between these micronutrients and effective cation exchange capacity.

Increase soil pH in acidic soils increases micronutrients availability in the soil due to increase in soil

biodiversity, organic matter decomposition, soil porosity and soil aggregation. Positive relationship between

organic carbon and these micronutrients could be attributed to the chelating property in organic matter that

helps to hold these nutrients in the soil. Similar observation was made by Verma et al., (2005) who recorded

positive significant correlation between Zn and organic carbon and attributed it to the complexing agents

generated by organic matter which promotes Zn availability in the soil. Increase in soil bulk density reduces

micronutrient availability due to its negative effects on soil microbial growth, soil aeration and water

infiltration. Organic matter is a reservoir of soil exchangeable cations and therefore increase in ECEC

increases micronutrients in the soil as observed by Yadav (2011).

0

0.5

1

1.5

2

2.5

3

3.5

Bo Zn Mn

0

0.557

1.057

0.12

0.905 1.07

0.777

1.588

3.13

Nu

trie

nt

con

cen

trst

ion

(m

g/kg

)

Micronutrients

Cassava cultivated land Maize cultivated land Forested land

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Table 3: Relationship between Selected Chemical Properties and Micronutrients

*&** significant at 0.05 and 0.01 probability levels respectively

4.0 Conclusion

Micronutrient availability is influenced by land use types due to differences in management practices. High

concentration of the studied micronutrients were found in forested land than cassava or maize dominated

farm lands and therefore, proper agronomic practices that will increase soil pH and organic matter in the area

should be practiced when lands are put into cultivation. Farmers should be encouraged to embrace organic

manuring and minimum tillage.

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