Green Manuring

Green Manuring
Green manuring is the practice of enriching the soil by

ploughing under or soil incorporation of any green manure
crops while they are green or soon after they start flowering.
The organic matter in the soil is recognized as being one of its
most valuable constituents for real soil fertility.
The decay of this organic matter influences the availability of
the soil nutrients.
Crops that are grown for green manure are called green manure
crops.
Green manuring has recently been under practice by our
farmers for decades.
40- 50 days old green manure crop can supply up to 80-100 kg.
N/ha. Even if half of this N is crop utilizable, a green manure crop
can be a substitute to 50-60 kg. fertilizer N/ ha.
Some of the potential green manuring legumes are dhanicha,

sunhemp, cowpea, mung, bean, guar and berseem etc.
Dhanicha, sunhemp, mung bean and guar grown during kharif

season as green manure crops have been reported to contribute
8-21 tones of green matter and 42-95 kg. of N/ha.
Similarly, Khesari, cowpea and berseem grown during rabi season

can contribute 12-29 tons of green matter and 67-68 kg of N/ ha
Classification of GM crops
A)Green leaf manuring Where the application of green
leaves and twigs of trees, shrubs and herbs collected from
plants grown in wastelands, field bunds, degraded lands
and nearby forest.
They are turned down or mixed into the soil 15-30 days
before sowing of the crops depending on the tenderness of
the foliage or plant parts is known as green leaf manuring
B) On–farm green manure or legume green manuring

The short duration legume crops are grown and buried in
the same site when they attain the age of 60-80 days after
sowing.
The legumes are preferred because of their ability to fix

nitrogen from the air. These include peas, clovers, lentils,
etc.
Advantages of GM
Increase soil organic matter through biomass production
Increase nutrient cycling
Leguminous crops adds N to the soil
Maintain or increase soil life through covering the soil as
"living mulch"
a) lower soil temperature, b) help retain soil moisture
Increase soil resilience
a) soil structure b) soil fertility c) moisture retention
Decrease inputs
can use locally available seed
25-40% decrease in chemical use
Reduced labor (while growing)
Potentially income generating

a) fodder for animals b) human food (pulses)
• Increase economic return (when adequately chosen).
• Reduce need to use herbicides and pesticides.
• Increase yield and improve quality of the following crops.
• Prevent soil erosion.
• Conserve soil humidity
• Maintain or increase soil organic matter content.
• Provide nitrogen to the soil.

• Improve soil fertility.
• Reduce fertilization costs

Disadvantages of GM
Slow results: benefits of a first-year GM/CC crop
often not seen until the next growing season
When intercropped, there may be competition

between crops
Unless GM/CC also produces food or income, it is

not always readily accepted
GENERAL REQUIREMENTS THAT SHOULD BE
MET BY GM CROPS
• Have low establishment and management costs.
• Be easy to sow and manage.
• Achieve good shading and weed suppression.
• Produce a favorable residual effect on cash and subsistence crops.
• Be rustic and require few crop management practices.
• Present good conservation characteristics.
• Avoid proliferation of pests and diseases.
• Avoid competition for land, labor, time, and space with cash or subsistence
crops.
Rapid growth and good soil cover under prevailing soil and climatic conditions.
• Production of a great quantity of green and dry mass, of the above-arts and
roots.
• Slow decomposition of dry matter produced.

Factors affecting GM
Factors
Biomass production of green manure crops varies due to
various factors such as
Species of the legumes,
Environmental conditions,
Soil fertility
Crop management practices and
Age of green manure crops

Techniques of green manuring in the field
•The maximum benefit from the green manure crop cannot be
obtained without knowing the:
•1) Right time of growing.
•2) Right time of incorporating in the soil.
•3) Time required for decomposition
•(a) Time of sowing of the green manure crop :
Time of sowing of the green manure crop varies according to local

conditions and resources available.
Normally, green manure crop is sown immediately after monsoon

rains.
But, if irrigation facility is available, green manure crop can be grown

as catch crop after harvesting of rabi crop during April and May.
Green manures and undersowing:
Undersowing involves growing a green manure at the same time as that of main crop.
Sometimes they are sown with the crop or slightly later when the crops are already
growing.
This reduces competition between the green manure and the crop.
No extra time is spent preparing the land and sowing the green manure.
(b) Stage of burying of green manure crop:
Burial of green manure crop at specific time provides maximum nitrogen and organic
matter.
This specific stage is when plant is immature and has started flowering.
During early period of crop growth, N content, protein, water soluble constituents are
maximum, whereas fibre, hemicelluloses, cellulose, lignin and C:N ratio are less.

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Green Manuring

Green manuring is the practice of enriching the soil by

Some of the potential green manuring legumes are dhanicha,

Dhanicha, sunhemp, mung bean and guar grown during kharif

Similarly, Khesari, cowpea and berseem grown during rabi season

B) On–farm green manure or legume green manuring

The legumes are preferred because of their ability to fix

Potentially income generating

• Reduce need to use herbicides and pesticides.

• Increase yield and improve quality of the following crops.

• Prevent soil erosion.

• Conserve soil humidity

• Maintain or increase soil organic matter content.

• Provide nitrogen to the soil.

• Reduce fertilization costs

When intercropped, there may be competition

Unless GM/CC also produces food or income, it is

• Be easy to sow and manage.

• Achieve good shading and weed suppression.

• Produce a favorable residual effect on cash and subsistence crops.

• Be rustic and require few crop management practices.

• Present good conservation characteristics.

• Avoid proliferation of pests and diseases.

• Slow decomposition of dry matter produced.

Species of the legumes,

Crop management practices and

Age of green manure crops

•(a) Time of sowing of the green manure crop :

Time of sowing of the green manure crop varies according to local

Normally, green manure crop is sown immediately after monsoon

But, if irrigation facility is available, green manure crop can be grown

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