Submitted By

Ramyajit Mondal

B.Sc(Ag.) Hons.,

7th Semester

Palli Siksha Bhavana

VISVA -BHARATI

ROLE OF SOIL ORGANIC MANURE

IN SUSTAINING SOIL HEALTH

Submitted To

Dr. N.C.Sarkar

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INTRODUCTION

Soils are dynamic ecosystems that support a diversity of life. Therefore, the concept

of soil health, like that of human health, is not difficult to understand or recognize when

the system is viewed as a whole. The challenge is to manage soils such that they are able

to perform the various uses they are put to without degradation of the soils themselves or

the environment.

The use of chemical fertilizers is increasing day by day for the sake of increasing

production. By excess use of chemical fertilizers, the fertility of soil and health also

deteriorate. Therefore the use of organic manure is one of the alternative ways for

enhancing production and improves the soil health. It is not only cheaper, easily available

and enhances agriculture too. Organic manures are natural products used by farmers to

enhance sustainable crop production. Organic manure increase organic matter in soil,

enables soil to hold more water and also helps to improve drainage in clay soil. Organic

manure increase to plant nutrient in soil. Thus organic manures helps in sustainable and

economic food production as well as sustainable agriculture.

DEFINITION OF SOIL HEALTH Doran and Parkin (in Doran et al., 1994) defined soil quality (health) as “the

capacity of a soil to function, within ecosystem and land use boundaries, to sustain

biological productivity, maintain environmental quality, and promote plant and animal

health.” It is worth noting here that “soil health” and “soil quality” are essentially

synonymous terms.

Soil organic matter is natural source of plant nutrients. Organic matter makes a soil

healthy, a healthy soil produces a crop healthy, and healthy crops nourish people well.

This article discusses little about role of organic matter in soil health.

Soil Organic Matter Organic material is anything that was alive and is now in or on the soil. Organic

material is unstable in the soil, changing form and mass readily as it decomposes. As much

as 90 percent of it disappears quickly because of decomposition. For it to become organic

matter, it must be decomposed into humus. In its broadest sense, soil organic matter

comprises all living soil organisms and all the remains of previous living organisms in their

various degrees of decomposition. Soil organic matter consists of a variety of components.

These include, in varying proportions and many intermediate stages, an active organic

fraction including micro-organisms (10–40 percent), and resistant or stable organic matter

(40–60 percent), also referred to as humus. The living organisms can be animals, plants or

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micro-organisms, and can range in size from small animals to single cell bacteria only a few

microns long.

Non-living organic matter can be considered to exist in four distinct pools:

Organic matter dissolved in soil water

Particulate organic matter ranging from recently added plant and animal debris to

partially decomposed material less than 50 microns in size, but all with an

identifiable cell structure.

Particulate organic matter can constitute from a few percent up to 25% of the total

organic matter in a soil

Humus which comprises both organic molecules of identifiable structure like

proteins and cellulose, and molecules with no identifiable structure (humic and

fulvic acids and humin) but which have reactive regions which allow the molecule

to bond with other mineral and organic soil components. These molecules are

moderate to large in size (molecular weights of 20,000 – 100,000). Humus usually

represents the largest pool of soil organic matter, comprising over 50% of the total.

NATURAL FACTORS INFLUENCING THE AMOUNT

OF ORGANIC MATTER & SOIL HEALTH The transformation and movement of materials within soil organic matter pools is

a dynamic process influenced by climate, soil type, and vegetation and soil organisms. All

these factors operate within a hierarchical spatial scale. Soil organisms are responsible for

the decay and cycling of both macronutrients and micronutrients, and their activity affects

the structure, tilth and productivity of the soil.

SALINITY AND ACIDITY -Salinity, toxicity and extremes in soil pH (acid or

alkaline) result in poor biomass production and, thus in reduced additions of organic

matter to the soil. For example, pH affects humus formation in two ways:

decomposition, and biomass production. In strongly acid or highly alkaline soils,

the growing conditions for micro-organisms are poor, resulting in low levels of

biological oxidation of organic matter. Soil acidity also influences the availability of

plant nutrients and thus regulates indirectly biomass production and the available

food for soil biota. Fungi are less sensitive than bacteria to acid soil conditions.

VEGETATION AND BIOMASS PRODUCTION-The rate of soil organic

matter accumulation depends largely on the quantity and quality of organic matter

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input. Under tropical conditions, applications of readily degradable materials with

low C:N ratios, such as green manure and leguminous cover crops, favour

decomposition and a short-term increase in the labile nitrogen pool during the

growing season. On the other hand, applications of plant materials with both large

C:N ratios and lignin contents such as cereal straw and grasses generally favour

nutrient immobilization, organic matter accumulation and humus formation, with

increased potential for improved soil structure development.

SOIL MOISTURE AND WATER SATURATION- Soil organic matter levels

commonly increase as mean annual precipitation increases. Conditions of elevated

levels of soil moisture result in greater biomass production, which provides more

residues, and thus more potential food for soil biota.

SOIL TEXTURE Soil organic matter tends to increase as the clay content increases.

This increase depends on two mechanisms. First, bonds between the surface of clay

particles and organic matter retard the decomposition process. Second, soils with

higher clay content increase the potential for aggregate formation. Macro

aggregates physically protect organic matter molecules from further mineralization

caused by microbial attack

TOPOGRAPHY Organic matter accumulation is often favoured at the bottom of

hills. There are two reasons for this accumulation: conditions are wetter than at

mid- or upper-slope positions, and organic matter is transported to the lowest point

in the landscape through runoff and erosion. Similarly, soil organic matter levels are

higher on northfacing slopes (in the Northern Hemisphere) compared with south-

facing slopes (and the other way around in the Southern Hemisphere) because

temperatures are lower.

MICROBIAL POPULATION This effects the soil health very much.it helps in

mineralization process in which the nutrients become available to the plants. If there

is low amount of microbes then this should be consider as low quality soil.

SOIL EROSION Soil erosion degrades the soil quality as well as soil health very

much. As in this process the fertile top soil is degraded and affect the organic matter

content.

DEFORESTATION For urbanization the forest area is gradually decreasing. It a

one of the reason of degrading organic matter as well as its health.

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LONG TERM EFFECT OF PESTICIDES AND CHEMICAL FERTILIZERS-

due to application of rapid pesticides and chemical fertilizers there is residue present

in soil which affects soil health.

LONG TERM EFFECT OF THE TILLAGE It is detrimental for soil health and

soil quality.

SELECTION OF CROP AND CULTIVARS selection of crops influence the

soil health as well as the organic matter. Different crops has the different

type of root system i.e. deep and shallow rooted crops which take

nutrients from different layers of soil. Thus if we practice proper crop

rotation then the health of soil can be maintained properly. Cultivation

of the erosion resistant crops can improve the productive soil.

CROPPING SYSTEM Avoiding of monocropping and practicing mixed

cropping helps to increase the soil health. Cultivation of cereals and

legumes modifies soil quality and increases the nutrient availability of

soil.

DIVERSITY IN FARMING SYSTEM IFS helps to improve the soil quality

by interconnected one enterprise to another enterprise. This also helps

to increase the farm income.

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CLASSIFICATION OF MANURE

Farm Yard Manure (FYM):

Incorporation of FYM resulted in build-up in Soil Organic Carbon.)A buildup of

organic carbon in the soil due to continuous application of manure and crop residues has

also been reported by several scientists. Application of FYM alone or with fertilisers has

improved physical, chemical and biological properties of soil. Application of FYM has

improved soil physical conditions viz., stable soil aggregates, density, soil moisture holding

capacity and soil air movement. FYM application also has a positive influence on the

nutrient availability. Available nitrogen content has a direct relationship with organic

carbon content of the soil.it also increase in available nitrogen with application of FYM,

and also observed improved nitrogen use efficiency. They also observed buildup of

available P2O5 in plots applied with FYM. The decomposition of FYM releases certain

compounds which help in enhanced dissolution of native P compounds. The build-up of

available P2O5 is attributed to this process. FYM application also has a positive influence

on available potassium. FYM is not only a direct and ready source but helps in minimizing

the leaching loss of K by retaining K ions on exchange sites.

Availability of major secondary and micro nutrients such as Calcium, Magnesium,

Sulphur, Zinc, Copper, Manganese and Iron increased in fields applied with FYM. In

Manure

Bulky OM

FYMCompost

Green Manuring Vermicompost

Concentrated OM

Plant Origin

Neem Cake

Mahua Cake

Mustard cake

Karanj Cake

Animal Origin

Bone Meal

Blood Meal

Meat Meal

Fish Meal

Guano

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addition to all these, the beneficial microbial population and enzyme activities were

enhanced significantly on application of FYM.

Compost

Composting is a advocated for recycling of different types of bio degradable organic

matter by converting them valuable manure.It is done by different aerobic & anaerobic

microorganism and have a optimum C:N ratio.

Green Leaf Manure (GLM)

Improvement in soil porosity and maximum water holding capacity (MWHC) was

recorded with Green Manure application in vertisols. Reduction in bulk density and

improvement in aggregate stability, extractable carbon, sugar and microbial biomass was

recorded (Prabhakar et al. 2002). With green manuring population of N2 fixers and

phosphate solubilizes increased considerably. Another study recorded a significant increase

in the bacterial population and microbial biomass of N in the soil amended with green

manures .Growing of legume as green manure helped to save 60 kg nitrogen for the

succeeding paddy crop.

BASED ON SUBSTRATE USED

Rural compost

Urban compost

BASED ON OXYGEN USED

Aerobic

Anaerobic

BASED ON TEMPERATURE

Mesophylic

Thermophilic

BASED ON TECHNOLOGY

Open Composting

Mechanical Composting

Classification Of Composting

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Vermicompopsting – Vermicomposting is a composting aided by

earthworm.As they consume 2-5 times of their body weight and a excret mucus coated

undigested matter known as vermicast. One tonnes of moist organic matter can converted

300kg of vermicompost.The main sps. of earthworm Eisenia foetida, Pheretima elongate

,eudrillus eugeniae etc. the vermicompost is very rich in different nutrients which helps the

soil health very much.And the earthworms are also known as the friend of farmers as well

as their presence in field indicates the very good physical, chemical, and biological status

of soil.

Liquid manures

Use of traditional knowledge based liquid manures viz., Panchagavya, Jeevamrutha,

Beejamrutha Amritpaani and biofertilisers in paddy with and without compost indicated

that, paddy yield obtained under organic farming was equal to research station yield.

Application of Panchagavya and Jeevamrutha to paddy at monthly interval has resulted in

lush green colour of the crop and the crop was fairly free from pest and diseases. Further,

the microbial population viz., N fixers, P solublisers and actinomycets were very high

compared to control plots.Cowdung is rich in agriculturally beneficial microorganisms.

Organic farmers in India widely prepare and use a traditional knowledge product Amrit

Paani (1kg dung, 1l urine, 50g jaggery made to 10l with water, stirred every day 4-5 times,

ready for use as soil applicant on day 4) and was found having high population (more

than 0.1 million per ml) of these bacteria.

Their population was at par or more than some of the inoculants manufactured by

bioproducts industry and sold in the market

Image: Panchagavya is prepared mainly using the five products of the cow - milk, curd,

ghee, urine and dung.

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Effects of Organic manures on Soil health-

Soil is a living, dynamic ecosystem and healthy soil is the foundation of the food

system. It produces healthy crops that in turn nourish people. Maintaining a healthy soil

demands care and effort from farmers because farming is not benign. Plants obtain

nutrients from two natural sources: organic matter and minerals. Soil organic matter (SOM)

and specifically soil organic carbon (SOC) are known to play vital role in the maintenance

as well as improvement of soil environment. Soil organic matter is a critical component of

the soil resource base, which affects the biological, chemical, and physical processes of the

soil and, through the effect on these processes, fulfils a very wide range of functions.

A. Effects on soil physical environment-

1. Soil structure and aggregate stability: Soil structural stability refers to the

resistance of soil to structural rearrangement of pores and particles when exposed to

different stresses. Soil structure is stabilized by a variety of different binding agents. Soil

organic matter is a primary factor in the development and modification of soil structure.

While binding forces may be of organic or inorganic origins, the organic forces are more

significant for building large, stable aggregates in most soils. Examples of organic binding

agents include plant and microbially derived polysaccharides, fungal hyphae, and plant

roots. Both the stable and the active fraction of SOM contribute to and maintain soil

structure and resist compaction.

2. Soil water regimes: It has been observed that soils with higher SOM are “fluffier”

or have better “tilth” than soils with less SOM. This is because SOM is less dense than the

mineral soil particles per unit of volume, and therefore provides greater pore space for

water and air to be held. The result of increasing SOM is greater soil pore space, which

provides an area for water to be stored during times of drought. A unique characteristic of

the pore space in SOM is that the pores are found in many different sizes. The large pores

do not hold water as tightly, and thus will drain more readily. The medium and small-

sized pores will hold water more tightly and for a longer period of time, so that during a

dry period the soil retains moisture and a percentage of that water is made available over

time for plant uptake. The benefit of leaving residue on the soil surface and increasing soil

organic matter is that water infiltration is increased, soil crusting is decreased, and the soil

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can hold more of the water that infiltrates and will eventually make it available for plant

use.

3. Soil Temperature: SOM imparts dark brown or black soil colour which is

important for ensuring good thermal properties, which in turn contribute to soil warming

and promote biological processes. Only about 10% of the solar energy reaching the earth’s

surface is actually absorbed by the soil, which can be in turn used to warm the soil.

Naturally, dark coloured soils absorb more energy than light colored ones. However, this

does not imply that dark coloured soils are always warmer, since dark coloured soils usually

have a higher amount of organic matter, which holds comparatively larger amounts of

water; a greater amount of energy is required to warm darker soils than lighter coloured

ones. Thus, the thermal property of soil is to a large degree influenced by water content,

Db, soil texture (fine versus coarse) and soil colour. In addition, the surface cover of soil

affects the heat transfer in and out of a soil. As bare soils warm up and cool off more

quickly than those with a vegetation or mulch cover. Thus presence OM acts as a insulator,

retarding heat movement between the soil and atmosphere.

4 Soil Air- It helps to increase the macro pores in soil which is the main source of the

plant root respiration.

5. Bulk Density- With increase in organic content in soil the bulk density decreases

which helps in ploughing. In surface soil there is more organic matter present, so bulk

density is less than sub soil. It reduces soil compaction.

B. Effects on soil chemical environment

1. CEC: The density of cation exchange capacity (CEC) of organic matter is greater than

it is for

clay minerals (Table 1). It has thirty times more cation absorption capacity than that of

mineral

colloids. The different functional groups viz. carboxylic acids (54%), phenolic and hydroxil

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groups (36%) and amide groups (10%) of SOM are believed to be one of the main

contributors to

CEC as they provide negatively charged sites.

Table 1:

Cation exchange capacity of different soil particles

Soil particle CEC (cmol/kg)

Humus 100-300

Smectites (black swelling clays) 60-150

Kaolinite (white potter’s clay) 2-15

Iron and aluminium oxides (from ferrosols) <1

The organic matter increase the nutrient holding capacity, which helps to maintain the

nutrient status of the soil.

2. Soil PH- It is the –ve log of active H+ ion in the soil solution. By intensive use of

fertilizers and as well as high rainfall the soil ph hampers very much. But the organic matter

has the buffering capacity to soil ph. Generally in alkaline soil the application of organic

manures helps the ph to become normal.

Organic Carbon- organic matters helps to enrich the soil with carbon which is a main food

for the microorganism. Organic carbon helps to maintain the ratio of C:N in soil which

helps to decompose the organic matter. 58% organic carbon present in organic matter.

3. Buffering capacity of soil: The availability of different functional groups (e .g.

carboxy lic, phenolic, acidic alcoholic, amine, amide and others) allows SOM to act as a

buffer over a wide range of soil pH values. Due to this, likelihood of damage to plant roots

from acids and salts, whether naturally present or added through fertilizers reduces.

4. Nutrients availability: OM accelerates decomposition of soil minerals over time,

making the nutrients in the minerals available for plant uptake. OM can be considered as

the store house of different nutrients; essential to plant growth. OM is the source of 90-95

per cent of the nitrogen in unfertilized soils. In addition, OM supplies available

phosphorus, sulphur and some other micronutrients like Fe, Mn, Cu and Zn ets to the soil

and thereby increases the nutrient regime as well as improves the soil health. The ratio of

carbon:nitrogen:sulphur:phosphorus in organic matter is roughly 100:10:1.5:1.5. A soil

which weighs 1,000,000 kg, with a carbon content of 1% would contain 1,000 kg of

organic nitrogen, and 150 kg each of organic phosphorus and sulphur per hectare. Not all

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of this is mineralized each year, but there is considerable potential for nutrients in organic

matter to contribute to plant requirements.

C. Effects on soil Biological Environment

Healthy soil is teeming with microscopic and larger organisms that perform many vital

functions including converting dead and decaying matter as well as minerals to plant

nutrients. Different soil organisms feed on different organic substrates. Their biological

activity depends on the organic matter supply. Soil organic matter is the driving force for

providing food for the living organisms in the soil, which enhances soil microbial

biodiversity and activity. Microorganisms only make up a small portion of the SOM (less

than 5%) they are imperative to the formation, transformation, and functioning of the

soil. In the soil, they conduct indispensable processes such as decomposition, nutrient

cycling, and degradation of toxic materials, N fixation, symbiotic plant relationships, and

pathogen control.

PHYSICAL FUNCTIONS

•Influence soil temperature

• Bind soil particles together in stable

aggregates

•Influence water holding and

aeration

CHEMICAL FUNCTIONS

• Source of pH buffering

• Major source of cation exchange

capacity

• Binding site for heavy metals and

pesticides

BIOLOGICAL FUNCTIONS

•Major reservoir of plant nutrien

•Food source for microbes and small

animals

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CONCLUSION:

There are several benefits of organic manure in improving soil quality and soil health and

the quality soil is the most important and primary input of crop production.

By intensive agriculture the organic matter status of soil declined day by day. So, to

improve the fertility status of soil, use of organic manure instead of inorganic chemical

fertilizer is a common practice and this concept originated along with the crop production.

Until mid of nineteenth century the organic manures were the only source of nutrient

required by the crop plants. Even today its application is supposed to be of prime

importance despite of tremendous advances made in the field of agriculture. Organic

manure improve soil quality by modifying soil physical property, increase biological

activity i.e, micro-organism activity, helps in decomposition of organic matter etc. Organic

manure helps plants to quick uptake of nutrients from soil, increase nutrient availability in

soil, reduces soil pollution, minimize soil erosion and degradation, improve nutritional

security and reduce many problems related to crop production. Lastly, we can say that

application of organic manure and practice of organic farming has a desirable effect on

sustainable food production.