What is green manuring? Give example of green manures

Green manuring is the agricultural practice of growing specific fast-growing plants and then ploughing or turning them into the soil while still green (before they flower or set seed) to improve soil fertility and structure. These plants, called green manure crops, are typically legumes or other nitrogen-rich species that are cultivated not for harvest but specifically to be incorporated back into the soil as organic matter. When decomposed, they release essential nutrients—particularly nitrogen, phosphorus, and potassium—while enhancing soil texture, water-holding capacity, and microbial activity. This practice is especially valuable in organic farming and sustainable agriculture systems where chemical fertilizers are avoided.

Common examples of green manure crops include legumes like dhaincha (Sesbania aculeata), sunn hemp (Crotalaria juncea), cowpea, and cluster beans, which have the added advantage of nitrogen fixation through their root nodules. Non-leguminous green manures such as jowar (sorghum) and maize can also be used, though they primarily contribute organic matter rather than nitrogen. A typical green manuring cycle involves sowing these crops during fallow periods or as inter-crops, allowing 6-8 weeks of growth, then ploughing them into the soil 2-3 weeks before planting the main crop. This technique not only reduces fertilizer costs but also suppresses weeds, prevents soil erosion, and improves the biological health of farmland, making it a cornerstone practice in regenerative agriculture.