Sunn Hemp: A Cover Crop for Southern and Tropical Farming Systems
Introduction Do you want a cover crop that will increase organic matter, provide nitrogen, grow in low fertility sandy soils, and does not harbor nematodes? Sunn hemp (Crotalaria juncea L.) is a legume that when grown as a summerannual can produce over 5,000 pounds of biomass and over 100 pounds of nitrogen per acre. Farmers only need 8 to 12 weeks of frost-free growth conditions to receive these results. Using a winter cover crop/green manure is a conservation practice that provides soil-improving characteristics. A common problem however, is that the relatively short period between cash crop harvest in the fall and planting the following spring can result in less than optimum biomass production of the cover crop. Sunn hemp, because of its rapid growth and relatively short growing season requirement, can be an excellent alternative. Where conditions are favorable, it can provide the benefits of a winter legume prior to a killing frost in the fall and also in the summer after the winte...