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

Abstract

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.