Green manuring, It's type and Advantage

Green manuring has effectively used the legume effect.

Ordinary green manure crops like Dhaincha, Sunhamp, and others may fix an average of roughly 60 kg/ha of nitrogen.

However, it is unlikely that the green manure crop’s accumulation of nitrogen will be sufficient to provide the quantity of nitrogen now required by high producing types. Therefore, the optimum approach is to combine the use of chemical fertiliser and green manuring.

Green manuring is the process of turning or ploughing green plant tissue that has not yet disintegrated into the soil in order to increase the soil’s physical health and fertility. The manures produced in this way are also known as green manures.

In China, records of the usage of green manure in agricultural production date back to 1134 BC.

Types of Green Manuring

Green manuring In-Situ

- Any crop or palnt (generally leguminous) grown and ploughed in situ is called green manuring in situ.
- E.g.: Sesbania (Sesbania speciosa), Dhaindia (Sesbania aculeate), Sunhemp (Crotolaria juncea), Phillipesara (Phaseolus trilobus), Cowpea (Vigna anguiculata), Green gram/Mungbean (Vigna radiata), Black gram (Vigna mungo), Berseem (Trifolium alexandrium) etc.

Green Leaf Manuring

- Consists of gathering green biomass (tender leaves and twigs) from nearby location (bunds, field boundaries) and adding it to the soil.
- E.g.: Cassia auriculata, Neem (Azadiracta indica), Glyricidia (Glyricidia maculate), Leucaena leucocephala, Cassia tora, Tephrosia purpurea, Vitex nigundo, Karanj (Pongamia glabra), Calotropis (Calotropis gigantea) etc,.

Green manures Green Leaf Manures

- E.g.-Dhaincha, Sunhemp, Glyricidia, Cassia, Green gram, Cowpea, Soybeam Pongamia glabra, Subabul.

Green manure Green Leaf Manure

- E.g. Sunflower, Sesbania, Calotropis, Adathoda, Buck wheat, Desmodium thespesia, Centroseme, Crotolaria

Advantages of Green Manuring

Helps in improving physical and chemical properties of soil. E.g. Builds up soil structure, improves tilth, formation of crumbs in heavy soil, increases water holding capacity.
Green manure crops absorb nutrients from the lower layer of soils and leave them in the soil surface layer when ploughed in for use by the succeeding crops.
Helps to maintain OM status of soil.
Acts as source of food and energy to soil microbes and increases their population.
Helps in release of nutrients in available form for use by the crops. E.g. GM crop increases the solubility of lime phosphate because of increase in microbial activity.
Prevents leaching of nutrients to lower layers.
Increases aeration of rice soils by stimulating the activities of surface films of algae and bacteria.
It reduces soil temperature and protects the soil from the erosion action of water as it forms canopy cover on the soil.
Leguminous green manure plants helps in N-fixation and adds the same to the soil. E.g. 60-100 kg N/ha in single season.
Green manures
- 60 to 200 kg N/ha.
- Crotolaria juncea (sun hemp)
- 17 t/ha biomass, 160 kg N/ha
Dhainchia (Sesbania aculeata)
- 25-26 t/ha biomass, 18.5 kg N/ha
Helps in soil amelioration. E.g. Sesbania aculcata (Dhaincha) in soil.
- when applied continuously for 4-5 seasons, green leaf manuring crops like Argenone maxicana and Tamarindus indicus has buffering effect in sodic soils.
Certain green manure like pongamia and neem leaves are reported to control insects.
Increases yield to the extent of 15-20 per cent compared to no green manuring.