The practice of ploughing or turning
into soil under-composed green plant tissue for the purpose of improving physical
condition as well as fertility of the soil is referred to as green manuring and
the manure obtained by this method is known as green manure.
The green manure crop should possess
the following desirable characteristics:
The green manure crops should
have profuse leaves and rapid growth
early in its life cycle.
have abundance and succulent tops
be capable of making a good stand
on poor and exhausted soils.
have a deep root system.
be legume with good nodular growth
Use of leguminous green manure crop
is more useful in comparison to non-legumes, as more nitrogen is added by legumes.
This will be advantageous for the soils and crops grown after green manuring.
Crops Suitable for Green Manuring
Crops suitable for green manuring
are divided into two groups:
Non-legumes or Non-leguminous crops:The
non-legumes used as green manuring crops provide only organic matter to the soil.
The non-legumes are used for green manuring to a limited extent. Examples:Mustard
(Brassica Sp), Wheat (Triticum Sp), Radish (Raphanus sativas), Carrot (Dancus carota),
Jowar (Sorghum Vulgare) Maize (Zea mays), Sunflower (Hellanthus annus), etc.
Legumes or Leguminous Crops:The legumes
used as green manuring crops provide nitrogen as well as organic matter to the soils.
Legumes have the ability of acquiring nitrogen from the air with the help of its
nodule bacteria. The legumes are most commonly used as green manuring crops. Examples:Sannhemp
(Crotalaira juncea), Djainach (Seshania aculata) Mung (Phaseolus aureus), Cowpea
(Vigna catjung), Lentil (Lens esculenta), Senji (Melilotus alba), Berseem (Phaseolus
aureus) Guar (Cyamposis tetragonolaba)
Benefits of Green Manuring:
There are numerous advantages of
Supply of Organic Matter:Green manure
supplies organic matter to the soil. The organic residues from green manure also help to provide the stability of soil structure needed for optimum plant growth.
Humus formed from green manure increases the absorptive capacity of soil, promotes
aeration, drainage and granulation, which help the plant growth. Green manuring
improves the structure of the soil. Organic matter stimulates the activity of soil
(ii) Addition of Nitrogen:The green
manuring crop supplies additional nitrogen to organic matter, if it is a legume
crop, which has the ability to fix nitrogen from the air with the help of its root
nodule bacteria (e.g. Rhizobium). The legume crop adds nitrogen for the succeeding
crop. So all the legumes crop leave the soil in better physical condition and richer
in nitrogen content. They return the plant nutrients of deeper layers to the upper
(iii) Nutrient and Soil Conservation:Green
manuring crops act as cover crop. They protect the soil from erosion and nutrient
loss by taking up soluble nutrients which might otherwise have been lost in drainage
water or due to erosion. Green manuring crops make available phosphorous and other
nutrients for the succeeding crops. Green manure has a marked residual effect also.
(iv) Increases the biochemical activity:The
organic matter added to soil by way of green manure acts as food for micro-organisms.
The organic matter stimulates the activity of micro-organisms and they stimulate
the biochemical changes accordingly.
(v) Green manuring increases crop
yield:Green manure increases the organic matter and nitrogen content (in case of
leguminous green manuring crop) of the soil.
It is proved that if green manuring
is done properly, it always results in increased yields of the succeeding crops.