Sunn Hemp as a Cover Crop and Nitrogen Source for Corn. (S-balkcom766694-oral)
Authors:
K.S. Balkcom* - USDA-ARS, Auburn, AL D.W. Reeves - USDA-ARS, Watkinsville, GA
Abstract:
The benefits of winter legumes as cover crops for corn (Zea mays L.) are
diminished by the earliness of corn planting in relation to biomass and nitrogen (N) production by the legumes. Tropical legumes may offer an alternative to winter legumes that produce adequate biomass prior to corn planting. We determined the suitability of ‘Tropic Sunn’ sunn hemp (Crotalaria juncea L.) as a cover crop for corn on a Compass loamy sand (coarse-loamy, siliceous, subactive, thermic Plinthic Paleudults) in central Alabama using a split-plot design of 4 replications from
1991-1993. Main plots were winter fallow and sunn hemp planted in mid-August, with N (0, 56, 112, and 168 kg N ha-1) applied 3 wk after corn planting (WAP) as sub-plots. Sunn hemp biomass production 12 WAP averaged 7.6 Mg ha-1 with an N content of 144 kg ha-1 in the first two years of the study. Corn grain yield following sunn hemp averaged 6.7 Mg ha-1 while yield following winter fallow averaged 5.6 Mg ha-1. Grain N uptake following sunn hemp averaged 17.2 kg ha-1 more than following fallow. A cover crop X N rate interaction occurred in 1991 for grain yield and in 1991 and 1992 for grain N uptake. Prior to first frost, sunn hemp produced adequate biomass to serve as a winter cover crop in corn production while producing 47 kg N equivalent ha-1 over the 3 y period. Sunn hemp has potential to be utilized as an alternative to winter legumes for ground cover and as an N source for a subsequent corn crop in the Southeast.
Speaker Information: Kip Balkcom, USDA-ARS, Auburn, AL, 411 S. Donahue Dr., Auburn, AL 36832; Phone: 334-844-4666; E-mail: [email protected]
