Cultivation of kenaf and sunn hemp in the mid-Atlantic United States

Sunn hemp (Crotolaria juncea L.), a legume plant, has potential in the mid-Atlantic region of the U.S. as a renewable source of fiber and pulp, due to its biological nitrogen fixation capability that can help reduce/eliminate N pollution of Chesapeake Bay. Most research in this region has focused on kenaf (Hibiscus cannabinus L.) and little is known about sunn hemp. We evaluated effects of three planting dates (late-May, mid-June, and late-June) and three row spacings (0.3, 0.6, and 0.9 m) on dry matter yields (DMY) of kenaf and sunn hemp during 1997, and 1998 by using three crop treatments (CT1: kenaf grown with 100 kg N ha−1; CT2: sunn hemp grown without inoculation and with 100 kg N ha−1; and CT3: sunn hemp inoculated with Bradyrhizobium but without N fertilization). DMY following CT1 and CT3 (7.8 and 6.4 Mg ha−1, respectively) during 1997 were similar and greater than that following CT2 (5.7 Mg ha−1). However, DMY following CT1, CT2, and CT3 were similar in 1998 and ranged from 12.6 to 13.4 Mg ha−1. Kenaf planting date did not affect DMY during 1997 but during 1998 the highest DMY was obtained from kenaf planted in late-May. The optimal planting date for sunn hemp during 1997 was mid-June, whereas in 1998 it was late-May. Row spacing effects on kenaf DMY were not significant. Row spacings of 0.3 m were optimal for DMY of N-fertilized sunn hemp during 1997 and 1998, whereas row spacing did not affect DMY of non-fertilized, but affected inoculated sunn hemp. We conclude that both kenaf and sunn hemp could produce similar dry matter yields in the mid-Atlantic region of U.S.