🌿 Organic Nutrient Management

This lesson builds core elective concepts in BSc Agriculture with practical applications and exam-oriented clarity.

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Organic Nutrient Management

Core Philosophy

The guiding principle of organic nutrient management is: "Feed the soil, not the plant." Rather than delivering soluble nutrients directly to the crop root zone as in conventional farming, organic systems aim to build soil organic matter, enhance microbial activity, and create a self-sustaining nutrient cycling system. Nutrients are released slowly as organic matter decomposes — matching crop demand while preventing leaching losses.

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Farmyard Manure (FYM)

FYM is the composted mixture of cattle dung, animal urine, feed refuse, and bedding material (straw or dry leaves). It is the most widely used organic amendment on Indian farms.

Nutrient Composition

• Nitrogen (N): 0.5–0.6%
• Phosphorus (P₂O₅): 0.3%
• Potassium (K₂O): 0.5%

Though the nutrient analysis appears low compared to chemical fertilizers, FYM delivers significant soil structural benefits — improving water-holding capacity, aeration, and microbial biomass.

Application

• Dose: 10–25 t/ha depending on crop and soil condition
• Timing: 2–4 weeks before sowing/transplanting; incorporate during last tillage
• Storage: Compost pit; cover to prevent nitrogen volatilization and nutrient leaching in rains; shade reduces drying

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Compost

Composting is the aerobic or anaerobic decomposition of organic materials by microorganisms into a stable, humus-rich amendment.

Key Principle: C:N Ratio

The Carbon-to-Nitrogen (C:N) ratio determines decomposition rate:

• Raw straw: 80:1 (too high C; decompose slowly, N immobilization)
• Green leaves: 30:1 (moderate)
• FYM: 25:1
• Target for finished compost: C:N of 12–15:1
• To achieve target: blend high-C materials (straw) with high-N materials (green manure, animal dung, kitchen waste)

Berkely Method (Hot Composting)

• Rapid composting: 18 days
• C:N ratio: 25–30:1 in the starting mix
• Temperature: 55–65°C (thermophilic phase kills pathogens and weed seeds)
• Frequent turning: every 2–3 days to maintain aerobic conditions
• Pile dimensions: 1.5 m wide × 1.5 m height (any length)
• Advantages: very fast; pathogen-free; high-quality compost
• Disadvantage: labor-intensive; requires careful material mixing

Indore Method (Albert Howard)

• Developed at Indore, Madhya Pradesh; described in "An Agricultural Testament" (1940)
• Duration: 3–6 months
• Layered composting: alternating layers of crop residue, animal manure, soil, and water
• Inoculation with a thin layer of old compost or soil at start to introduce microbes
• Pit or surface heap; turned 2–3 times during decomposition
• Suitable for India: simple, low-input, scalable; traditional practice
• Foundation of modern aerobic composting

NADEP Compost (Narayan Deotao Pandhari Palekar)

• Tank-based composting developed by Narayanrao Pandhari Palekar (Maharashtra)
• Brick tank: 12 ft × 5 ft × 3 ft
• Inputs: farm waste (70%) + soil (25%) + water (5%); cow dung slurry for inoculation
• Duration: 90–120 days; no turning required
• Advantage: uses minimal dung; converts large volumes of farm waste; low labour

Quality of Finished Compost

• Colour: black to dark brown
• Smell: earthy (musty), not foul
• Texture: crumbly, not slimy or fibrous
• Volume reduction: ~60% from original pile
• C:N ratio: <15:1

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Vermicompost

Vermicompost (VC) is produced by the breakdown of organic matter through the combined action of earthworms and microorganisms.

Key Species

• Eisenia foetida (red wiggler / tiger worm): most widely used; surface feeder; cosmopolitan
• Eudrilus eugeniae (African nightcrawler): larger; faster processor; suits tropical India
• Lumbricus rubellus: common in cooler climates

Production Process

1. Prepare bedding (coir, straw, partially composted FYM)
2. Introduce organic waste (vegetable scraps, crop residues, cow dung — no meat/oily waste)
3. Add worms at 500 g worms per square foot of bed area
4. Maintain temperature: 20–28°C; moisture: 60–70%; dark conditions
5. Turn and water regularly
6. Harvest after 45–60 days: castings appear as dark granules; worms retreat to lower layer
7. Separate worms using light (worms move away from light)

Nutrient Content

• N: 2–3%
• P₂O₅: 1–2%
• K₂O: 1.5–2%
• Additionally: plant growth hormones (gibberellins, cytokinins, auxins), beneficial microorganisms, humic acids, enzymes

Application and Economics

• Dose: 2.5–5 t/ha; applied as basal or as potting mix component
• Commercial value: ₹8–12/kg; strong demand in organic and urban horticulture markets
• Vermicompost improves: soil structure, water-holding capacity, CEC, root development, seed germination

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Green Manuring

Green manuring involves growing leguminous or non-leguminous crops and incorporating them into the soil while still green to improve soil fertility.

Types

In-situ green manuring (grown and incorporated in the same field):

• Sesbania aculeata (Dhaincha): adds 100–150 kg N/ha; fast-growing; tolerates flooding; ideal before paddy
• Crotalaria juncea (Sunn hemp): adds 80–100 kg N/ha; also a natural nematicide
• Tephrosia purpurea: leguminous; tolerates poor soils
• Vigna radiata (Mung bean): dual-purpose — harvest pods, incorporate residue

Ex-situ green manuring (leaves/biomass brought from outside):

• Gliricidia sepium: hedge plant; lop leaves for mulch or incorporation
• Leucaena leucocephala (Subabool): high-biomass; allelopathic to some weeds

Best Practice

• Incorporate at 50% flowering stage — highest N content, optimal decomposition rate
• Irrigate after incorporation to accelerate decomposition
• Contributes 40–150 kg N/ha depending on species and biomass

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Biofertilizers in Organic Farming

Biofertilizers are permitted under NPOP as they are living microbial cultures that enhance nutrient availability — no synthetic chemistry involved.

Biofertilizer	Mechanism	Crop Use
Rhizobium	Biological N fixation in root nodules	All legume crops
Azospirillum	Associative N fixation; growth hormones	Cereals, millets, sugarcane
Azotobacter	Free-living N fixation; produces vitamins	Non-legumes; soil application
PSB (Phosphate Solubilizing Bacteria)	Solubilizes fixed soil phosphate	All crops
VAM / AMF (Vesicular Arbuscular Mycorrhiza)	Extends root surface area; P, Zn uptake	All crops; highly beneficial in organic
Trichoderma	Biocontrol + phosphate/zinc solubilization	Soil application; seed treatment

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Liquid Manures and Biostimulants

Jeevamrit (ZBNF)

• Recipe: 10 L water + 1 kg fresh cow dung + 200 mL cow urine + 2 kg jaggery + 2 kg gram flour (besan) + handful of bund soil
• Fermentation: 48 hours in shade; stir twice daily
• Application: 200 L/acre/month via irrigation water or soil drench; colonizes soil with beneficial microbes
• Function: microbial inoculant; activates soil biology; provides micronutrients

Panchagavya

• Five cow products: dung + urine + milk + curd + ghee; fermented together
• Used as a biostimulant: foliar spray or soil drench
• Improves plant immunity, root growth, and yield
• Not standardized scientifically; used widely in traditional organic systems

Fish Amino Acid (Korean Natural Farming)

• Fermented fish + brown sugar (1:1); fermented 3–6 months
• Rich in amino acids, beneficial microbes
• Foliar spray at 1:500–1:1000 dilution; boosts protein synthesis in plants

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Nutrient Management Plan in Organic Farming

A systematic approach to managing fertility in organic systems:

1. Soil testing: baseline NPK, organic carbon, micronutrients; pH
2. Crop nutrient demand: calculate expected N, P, K requirement for target yield
3. Organic input audit: inventory of available manures, compost, green manures on farm
4. Balance calculation: map organic sources against crop demand; identify shortfalls
5. Input sourcing: supplement shortfalls with purchased VC, biofertilizers, rock phosphate
6. Record keeping: all inputs applied, dates, quantities — required for certification

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Major Organic Amendments — Summary Table

Amendment	N (%)	P₂O₅ (%)	K₂O (%)	Rate (t/ha)	Application Method
FYM	0.5–0.6	0.3	0.5	10–25	Basal; soil incorporation
Compost	1.2–1.8	0.5–0.8	0.8–1.2	5–10	Basal; top dressing
Vermicompost	2–3	1–2	1.5–2	2.5–5	Basal; potting mix; drench
Poultry manure	2.5–3.5	2.5–3.0	1.5–2.5	2–5	Basal; incorporate
Neem cake	5–6	1.0	1.5	0.1–0.25	Basal; also pest control
Sesbania (green manure)	2.5–3.5 (plant)	—	—	20–30 t biomass/ha	In-situ incorporation
Rock phosphate	—	20–30 (total P)	—	0.25–0.5	Basal; acidic soils

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Key Facts for Examination

• Berkely composting method duration: 18 days
• Indore method duration: 3–6 months; developed by Albert Howard
• NADEP compost tank dimensions: 12 × 5 × 3 ft
• Earthworm species for vermicomposting: Eisenia foetida (red wiggler)
• Sesbania N contribution: 100–150 kg N/ha
• Jeevamrit fermentation time: 48 hours
• One desi cow sufficient for Jeevamrit for: 30 acres (Palekar)
• Finished compost C:N ratio: <15:1

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Summary Cheat Sheet

Topic	Key takeaway
Main focus	FYM, compost methods (Berkely, Indore, NADEP), vermicompost, green manuring, biofertilizers, liquid manures, and nutrient management planning in organic systems.
Section context	Revise this lesson with the rest of Organic Nutrient Management for stronger conceptual continuity.