Wednesday, November 7, 2007
320-3
Biomass N Contribution of Cover Crops for Agronomic Crop Production.
Y. Raut1, J. Hoorman2, Alan Sundermeier3, Irfan Aziz4, and Khandakar Islam3. (1) The Ohio State University South Centers, 1864 Shyville Road, Piketon, OH 45661, (2) The Ohio State University Extension Center at Lima, 1219 W Main Cross, Findley, OH 45840, (3) Ohio State University - OARDC, 639 S Dunbridge Road Ste 1, Bowling Green, OH 43402, (4) Dept. of Agronomy, University of Arid Agriculture, Rawalpindi, 46300, Pakistan
Cover crops are important sources of nitrogen. This study was conducted to evaluate Alfalfa (Medicago sativa), Austrian Winter Pea (Pisum sativus), Cowpea (Vigna unguiculata), Crimson clover (Trifolium incarnatum L), Hairy vetch (Vicia villosa Roth), Ladino White Clover (Trifolium repens L), Mungbean (Vigna radiate, L.), and Red Clover (Trifolium Pratense) as suitable cover crops that would establish quickly, over-winter or winter-killed, and contribute sufficient biomass N for subsequent cereal crops during 2002 to 2006. At their maximum vegetative growth, both above- and below-ground biomass of cover crops were randomly harvested, oven-dried at 550C, ground and analyzed for C and N contents. Above-ground dry biomass production ranged from 1670 (Latino White Clover) to 7830 kg ha-1 (Cowpeas) Biomass N concentration ranged from 19.7 (Cowpeas) to 43.2 g kg-1 (Mungbean). Alfalfa had the lowest biomass C:N ratio at 11.3:1 while Cowpeas had the highest C:N ratio at 21.6:1.. Biomass N contribution ranged from 26.3 (White Clover) to 218 kg ha-1 for Alfalfa. Based on biomass production, N content, and suitability of planting and killing Cowpeas was planted as a cover crop after harvesting wheat in the3rd week of July in a wheat-corn-soybean rotation with or without chemical N fertilization under conventional tillage (CT) and no-till systems (NT). The Cowpeas biomass was winter killed (1st week of November). Results showed that there was no significant corn yield (7190 kg ha-1 vs. 7156 kg ha-1) difference between conventionally-tilled and fertilized treatment (CT-C) vs. no-till cover cropped treatment (NT-CC) with Cowpeas. However, corn yield was significantly lower (4577 and 6575 kg ha-1) in both reduced tillage (RT-C) and no-till (NT-C) treatments with chemical fertilization.