What is green manure? Give example

Green manure refers to crops that are grown specifically to be plowed back into the soil while still green and before they mature, decomposing in place to add organic matter and nutrients to the soil. This practice enhances soil structure, increases nitrogen content (especially when legumes are used), improves water retention capacity, suppresses weeds, and stimulates beneficial soil microbial activity. Green manuring is an ancient, cost-effective, and environmentally friendly method of maintaining soil fertility without relying heavily on synthetic fertilizers.

Common green manure crops include dhaincha (Sesbania aculeata), sunn hemp (Crotalaria juncea), cowpea, cluster beans (guar), and berseem, with leguminous plants being particularly effective due to their symbiotic relationship with nitrogen-fixing bacteria. For example, dhaincha is widely grown in rice-growing regions where it is sown before the monsoon, allowed to grow for 6-8 weeks, and then plowed into the waterlogged fields before rice transplantation. As the green matter decomposes, it releases nitrogen and other nutrients, reduces the need for chemical fertilizers by 25-30%, and improves the physical and biological properties of the soil, leading to better crop yields and long-term soil health.