The idea of green manuring is simple. We grow crops on the soil when it is not otherwise employed to later return them to enrich the soil. This costs very little except the seed, which can be self saved, and the effort brings many benefits. Sunlight energy and water is turned into biomass, the soil is protected from erosion and weeds are excluded. The only minor hitch is that green manuring has been developed mostly by farmers rather than by gardeners. So we have been recommended to use such delights as Hungarian grazing rye, tares and vetches, and clovers.