Submitted to: Agronomy Society of America, Crop Science Society of America, Soil Science Society of America Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 11/4/2007
Publication Date: 11/4/2007
Citation: Sainju, U.M., Singh, B. 2007. Cover crops and nitrogen fertilization effects of nitrogen conservation in tilled and non-tilled soils. Agronomy Society of America, Crop Science Society of America, Soil Science Society of America Meeting, November 4-8, 2007. New Orleans, Louisianna. Ppaer no. 309-9. p. 156.
Technical Abstract: Higher cost of N fertilization due to increase in the price of petroleum and increased N leaching from croplands necessitate that soil N be conserved and N fertilization rate be reduced. Proper crop and N management practices may increase soil N conservation and reduce N fertilization rate. We examined the influence of four cover crops [hairy vetch, rye, vetch + rye, and no cover crop (or winter weeds)] and three N fertilization rates (0, 60 to 65, and 120 to 130 kg N ha-1) on N inputs from cover crops, cotton and sorghum and soil total N (STN) content in tilled and non-tilled soils from 2000 to 2002 in central Georgia. Nitrogen inputs were greater in vetch and vetch + rye with N rates than in rye and weeds with or without fertilizer N, regardless of tillage. The STN concentration decreased with depth and varied with date of sampling. The STN content at the 0 to 90 cm depth was greater in vetch and vetch + rye with N rates than in weeds with or without fertilizer N in no-tilled and chisel-tilled soils and at 0 to 30 cm was greater with vetch and vetch + rye than with weeds in strip-tilled soils. As a result, soil N at 0 to 30 cm can be can be conserved at 71 to 108 kg N ha-1 yr-1 with vetch and vetch + rye compared with a loss at 48 to 110 kg N ha-1 yr-1 with weeds, regardless of N rates and tillage. Because of similar crop biomass N content and STN levels between vetch and vetch + rye and between 60 to 65 and 120 to 130 kg N ha-1, vetch can be replaced by vetch + rye and N fertilization rate can be reduced to sustain cotton and sorghum N uptake, maintain soil N storage, and reduce the cost of N fertilization and the potential for N leaching.