Sunn hemp is adapted to a wide range of soils and performs better on poor sandy soils than most crops. It is for such situations that it has attracted attention. It grows best on well-drained soils with a pH from 5 to 7.5. Sunn hemp has been used extensively as a soil improvement or green manure crop in the tropics because of its ability to produce large amounts of biomass in as little as 60 to 90 days. Because of this, it has the potential to build organic matter levels and sequester carbon. Also, as a legume, it can fix large amounts of nitrogen. Used as a cover crop, sunn hemp can improve soil properties, reduce soil erosion, conserve soil water, and recycle plant nutrients. Other potential uses for sunn hemp are forage, paper fiber, and as an alternative fuel crop.
As a cover crop, sunn hemp can produce 5,000-6,000 pounds of biomass per acre in southern climates in 60-90 days. It also can produce 120-140 pounds of nitrogen in the same amount of time. It provides the benefits of a cover crop such as erosion control, soil improvement, plus resistance to rootknot nematode. It requires warm weather for 8 to 12 weeks. It will be advisable to grow crops such as small grains after it because of the nitrogen production.