Planting Date and Seeding Rate Effects on Sunn Hemp Biomass and Nitrogen Production for a Winter Cover Crop

[摘要] Sunn hemp (Crotalaria junceaL.) is a tropical legume that produces plant biomass and nitrogen (N) quickly. Our objectives were to assess the growth of a new sunn hemp cultivar breed to produce seed in a temperate climate and determine the residual N effect on a rye (Secale cerealeL.) cover crop in east-central Alabama from 2007 to 2009.Plant populations, plant height, stem diameter, biomass production, and N content were determined for two sunn hemp planting dates, following corn (Zea maysL.) and wheat (Triticum aestivumL.) harvest, across different seeding rates (17, 34, 50, and 67 kg/ha). Rye biomass was measured the following spring. Sunn hemp biomass production was inconsistent across planting dates, but did relate to growing degree accumulation. Nitrogen concentrations were inversely related to biomass production, and subsequent N contents corresponded to biomass levels. Neither planting date nor seeding rate affected rye biomass production, but rye biomass averaged over both planting dates following wheat/sunn hemp averaged 43% and 33% greater than rye following fallow. Rye biomass following corn/sunn hemp was equivalent to fallow plots.Early planting dates are recommended for sunn hemp with seeding rates between 17 and34 kg/ha to maximize biomass and N production.

[学科分类] 农艺学与作物科学