What is green manure?

Green manure refers to certain plants or crops that are grown exclusively to be turned into the soil or allowed to decompose on the soil surface as mulch to enrich the soil with nutrients and organic matter. A few plants often grown as green manure include clover, oats, buckwheat, winter wheat, beans and peas. Many of these green manure crops are legumes, which add nitrogen to the soil. Green manures have similar benefits and uses as dynamic accumulators and cover crops.