What is green manuring and can I do it in pots?

Green manuring involves sowing fast-growing legumes (moong, cowpea, or sunn hemp), then cutting and digging them into the soil before flowering. In pots, sow moong in the inter-season gap, let it grow 20–25 days, cut it at soil level, and fork it into the top 10 cm. It adds nitrogen and improves soil structure cheaply.