All three crops can serve as pulse (for food), fodder (for animals), and green manure (ploughed back into soil for nitrogen fixation). Green manure crops are nitrogen-fixing legumes. Pigeon pea is in some areas an important crop for green manure, providing up to 40 kg nitrogen per hectare. The woody stems of pigeon peas can also be used as firewood, fencing and thatch. Cowpea and green gram are also well-known for all three uses.