♻️ Manures: Types and Classification

Manures improve soil fertility by supplying nutrients gradually while also strengthening soil physical and biological health. This lesson classifies major manure types and explains their practical use in crop production.

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Quick Answer: What Are the Main Types of Manures?

Manures are organic materials added to soil to improve nutrient supply, organic matter, soil structure, microbial activity, and water-holding capacity. In BSc Agriculture, the most useful classification is into bulky organic manures and concentrated organic manures.

Type	Nutrient Concentration	Application Rate	Main Examples	Best Use
Bulky organic manures	Low nutrients, high volume	Applied in tonnes per hectare	FYM, compost, vermicompost, green manure, sewage sludge	Improve soil physical condition and supply slow-release nutrients
Concentrated organic manures	Higher nutrients, lower volume	Applied in smaller quantities	Oil cakes, bone meal, blood meal, fish meal, poultry manure	Supply specific nutrients more quickly than bulky manures

Meaning of Manure

The word manure is derived from the French word manoeuvrer, meaning to work or manipulate. In agriculture, manure refers to organic material of plant, animal, or biological origin used to improve soil fertility. Traditionally, the term was used for animal excreta, but in soil science it includes FYM, compost, green manure, vermicompost, oil cakes, and other organic nutrient sources.

Unlike fertilizers, manures generally contain nutrients in lower concentration but improve the soil as a living system. They add carbon, support microbes, improve aggregation, reduce bulk density, and slowly release nutrients as they decompose.

Classification of Manures

Older texts classify manures by source, nutrient content, nutrient element, material, and action. These classifications are useful, but they often overlap.

Basis of Classification	Types	Meaning / Example
Nature of source	Natural, artificial, mineral	FYM is natural; some processed amendments are artificial; lime/gypsum are mineral amendments.
Nutrient content	Single, compound	Single manures mainly supply one nutrient; compound manures supply more than one.
Nutrient element present	Complete, incomplete	Complete manures contain N, P, and K; incomplete manures lack one or more major nutrients.
Nature of material	Organic, inorganic, indirect	Organic manures add organic matter; indirect manures improve nutrient availability or soil condition.
Nature of action	General, special, stimulative, soil amendments	General manures improve overall fertility; amendments correct soil problems such as acidity or sodicity.

Bulky Organic Manures

Bulky organic manures are natural organic materials applied in large quantities because their nutrient percentage is low. Their main value is not only NPK supply but also improvement of soil organic matter and physical condition.

Manure	Source	Approximate Nutrient Content	Main Benefits	Limitation
Farmyard manure (FYM)	Dung, urine, litter, and leftover feed from cattle or other farm animals	About 0.5% N, 0.2-0.25% P2O5, 0.5% K2O	Improves structure, moisture retention, microbial activity, and slow nutrient supply	Nutrient losses occur if poorly stored
Compost	Decomposed crop residues, weeds, farm waste, municipal organic waste	Variable; usually low to moderate NPK	Recycles waste and improves humus	Poor composting may carry weed seeds/pathogens
Vermicompost	Organic waste decomposed with earthworms	Richer and more biologically active than ordinary compost	Fine texture, plant-growth-promoting microbes, good for nurseries	Earthworms require controlled moisture and temperature
Green manure	Green crop grown and incorporated into soil	Adds organic matter and biologically fixed N in legumes	Improves soil N and structure; useful before rice and other crops	Occupies land and time before main crop
Green leaf manure	Leaves/twigs collected from trees and shrubs	Variable	Useful where green manure crop cannot be grown in the field	Transport and collection labour

Farmyard Manure (FYM)

Farmyard manure is the decomposed mixture of animal dung, urine, bedding material, litter, and leftover feed. It is one of the oldest and most widely used manures in Indian agriculture.

Composition of FYM

The average composition of well-rotted FYM is around:

Nutrient	Approximate Content
Nitrogen (N)	0.5%
Phosphorus (P2O5)	0.2-0.25%
Potassium (K2O)	0.5%

Actual nutrient content varies widely because FYM quality depends on animal feed, bedding material, age and condition of animals, urine collection, storage method, and decomposition.

Factors Affecting FYM Quality

Factor	Effect on Manure Quality
Source animal	Cattle, buffalo, sheep, goat, and poultry manures differ in nutrient concentration.
Feed quality	Nutrient-rich feed gives nutrient-rich manure.
Bedding/litter	Straw, leaves, and crop residues add carbon and absorb urine.
Urine collection	Urine contains much of the nitrogen and potassium; loss reduces value.
Storage method	Open heaps lose nitrogen through volatilization and leaching.
Degree of decomposition	Well-rotted FYM is safer and more uniform than fresh manure.

FYM Collection and Storage Methods

Method	Key Feature	Suitability
Ordinary cattle shed with kachcha floor	Dung and urine mix with soil	Common but causes nutrient loss.
Impermeable floor with urine pit	Urine is collected separately	Better nutrient conservation.
Dry earth system	Dry soil absorbs urine	Useful where bedding material is limited.
Loose box system	Animals remain on bedding; manure accumulates	Produces richer manure if managed well.
Heap method	FYM is stored above ground	Easy but more exposed to loss.
Pit method	FYM is stored in pits	Better moisture and nutrient conservation.

How to Reduce FYM Nutrient Losses

• Use an impermeable floor and collect urine.
• Store manure in pits or compact covered heaps.
• Keep FYM moist but not waterlogged.
• Mix absorbent bedding such as straw or dry soil.
• Use well-decomposed FYM instead of fresh material.
• Add preservatives such as gypsum or superphosphate where locally recommended.
• Use dung in biogas plants, then apply the slurry to fields.

Compost

Compost is prepared by controlled decomposition of organic wastes such as crop residues, weeds, leaves, animal wastes, market waste, pressmud, and household biodegradable waste.

Composting Material	Examples
Agricultural wastes	Paddy straw, sugarcane trash, weeds, pulse residues
Animal husbandry wastes	Dairy waste, goat/sheep waste, poultry litter, piggery waste
Agro-industrial wastes	Pressmud, coir pith, fruit and vegetable processing waste, sago industry waste
Municipal organic wastes	Household biodegradable waste, market waste, vegetable/fruit/flower waste

Good composting reduces volume, kills many weed seeds and pathogens through heat, stabilizes organic matter, and converts waste into a safer soil amendment.

Green Manures

Green manuring means growing a crop and incorporating it into the soil while it is still green and tender. Leguminous green manure crops are especially valuable because they add nitrogen through biological nitrogen fixation.

Green Manure Crop	Common Use
Dhaincha (Sesbania aculeata)	Common green manure before rice
Sunhemp (Crotalaria juncea)	Fast-growing green manure and fibre crop
Cowpea	Green manure and fodder option
Green gram / Black gram	Short-duration legumes that add residues and nitrogen
Gliricidia leaves	Green leaf manure in orchards and field bund systems

Concentrated Organic Manures

Concentrated organic manures contain higher nutrient percentages than bulky manures, so they are applied in smaller quantities.

Manure	Source	Main Nutrient Value	Notes
Oil cakes	Residue after oil extraction from seeds	Rich in N; also contain P and K	Neem cake also has pesticidal/nitrification-inhibiting value.
Bone meal	Steamed or raw animal bones	Rich in phosphorus and calcium	Slow-release P source.
Blood meal	Dried animal blood	Rich in nitrogen	Quick organic N source but less commonly used in field crops.
Fish meal	Processed fish waste	N and P source	Used more in high-value systems.
Poultry manure	Poultry droppings and litter	Higher NPK than cattle FYM	Must be composted or applied carefully to avoid burning.

Edible vs Non-Edible Oil Cakes

Category	Examples	Use
Edible oil cakes	Groundnut cake, sesame cake, coconut cake	Often used as cattle feed first; manure use depends on availability.
Non-edible oil cakes	Neem cake, castor cake, mahua cake, karanj cake	Commonly used as organic manure; neem cake is especially valued.

Manures vs Fertilizers

Feature	Manures	Fertilizers
Nutrient concentration	Low to moderate	High
Quantity applied	Large	Small
Nutrient release	Slow, through decomposition	Faster and more directly available
Organic matter	Adds significant organic matter	Usually does not add organic matter
Soil physical effect	Improves structure, aeration, water holding	Little direct improvement
Best role	Long-term soil health + nutrient supplement	Precise nutrient correction

Summary Cheat Sheet

Topic	Key exam point
Meaning of manure	Organic material added to soil mainly to improve fertility and physical condition
Main classification	Bulky organic manures and concentrated organic manures
Bulky manure examples	FYM, compost, vermicompost, and green manures
Concentrated manure examples	Oilcakes, blood meal, fish meal, bone meal
Key feature of bulky manures	Low nutrient analysis but strong effect on soil physical properties and microbial activity
Key feature of concentrated manures	Higher nutrient concentration than bulky organic manures
FYM point	One of the most common farm manures used to supply nutrients and improve soil structure
Manures vs fertilizers	Manures are mostly organic and low-analysis; fertilizers are manufactured/high-analysis nutrient sources
Soil benefit	Improve water holding, aeration, aggregation, and biological activity
Exam trap	Do not confuse classification by source with classification by nutrient concentration

References

3 sources • [1] [2] [3]

[1]

Indian Council of Agricultural Research (ICAR)

Official

[2]

Principles of Soil Science and Agricultural Chemistry — Standard BSc Agriculture Textbook

Book

[3]

Department of Agriculture & Farmers Welfare

Website