Sweet clovers produce abundant biomass and moderate amounts of nitrogen. Its taproot branches deep into subsoil layers. It is the most drought resistant of forage legumes, which thrives in temperate regions wherever summers are mild.
There are biennial, summer annual and winter annual species of sweet clover. They are known their abilities as soil builders, fertility sources, subsoil aerators and erosion preventers.
Biennial yellow sweet clover can produce over 7 tons of dry matter in its year of establishment. Annual sweet clover is not frost tolerant but can produce up to 10 tons of dry matter over a summer after being over-sown into a grain crop.