🌿 Green Manures and Green Leaf Manuring

Green manuring is a major agronomic practice for improving soil fertility, recycling nutrients, and strengthening low-cost nutrient management. It is especially important where organic matter, nitrogen supply, and soil condition need improvement.

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Green Manuring vs Green Leaf Manuring

Green manuring

Green manuring means:

• growing a crop specifically for soil incorporation
• ploughing it into the soil while still green

Green leaf manuring

Green leaf manuring means:

• collecting green leaves or tender biomass from outside sources
• incorporating them into the soil for manurial effect

This distinction is basic and frequently asked in exams.

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Why Green Manures Matter

Green manures are important because they:

• add organic matter
• help supply biologically fixed nitrogen in legume-based systems
• improve soil structure
• recover nutrients from lower soil layers
• help reduce nutrient losses between crops

They are part of a broader low-cost soil-fertility strategy, not just a single practice.

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Agronomic Importance of Leguminous Green Manures

Leguminous green-manure crops are especially valuable because they:

• fix atmospheric nitrogen
• produce decomposable biomass
• improve the nitrogen economy of the next crop

Their biomass usually decomposes faster than many coarse residues, which helps quick nutrient cycling.

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Where Green Manures Fit

Green manures can be fitted into:

• rainfed drylands
• irrigated drylands
• wetland rice systems

The choice depends on:

• water availability
• time available between main crops
• crop duration
• biomass potential

This is why green manuring is a systems-management practice, not just a crop choice.

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Major Green-Manure Crops

Important green-manure crops commonly discussed in South Indian agronomy include:

• daincha
• Sesbania speciosa
• Sesbania rostrata
• Tephrosia purpurea
• Indigofera
• sunnhemp
• Vigna trilobata in special situations

These crops differ in:

• drought tolerance
• waterlogging tolerance
• biomass production
• duration
• suitability for rice or dryland systems

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Green Leaf Manuring Sources

Green leaf manuring often uses biomass from:

• leguminous trees
• shrubs
• live fences
• locally available perennial sources

Examples often discussed include species such as:

• pungam
• gliricidia
• subabul
• cassia and others

The key agronomic idea is that the biomass source may be external to the field where it is incorporated.

Summary Cheat Sheet

• Green manuring means growing a crop and incorporating it into the soil while green.
• Green leaf manuring means collecting green biomass from outside sources and applying it to the field.
• Green manures help improve organic matter, soil condition, and nitrogen supply.
• Leguminous green manures are especially important because they fix atmospheric nitrogen.
• Green manures can fit into rainfed, irrigated, and wetland systems.
• Major green-manure crops include daincha, Sesbania spp., sunnhemp, and Tephrosia.
• Green leaf manuring often uses tree or shrub biomass like pungam, gliricidia, and subabul.
• The practice is part of low-cost nutrient management.
• Choice of crop depends on duration, water, and system fit.
• This is a classic example of soil-fertility agronomy.

References

2 sources • [1] [2]

[1]

ICAR e-Course: Agronomy

[2]

Ministry of Agriculture & Farmers Welfare