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ARS Home » Plains Area » Sidney, Montana » Northern Plains Agricultural Research Laboratory » Agricultural Systems Research » Research » Publications at this Location » Publication #198555
Title: TILLAGE, COVER CROPS, AND NITROGEN FERTILIZATION EFFECTS ON SOIL NITROGEN AND COTTON AND SORGHUM YIELDS

Author
item Sainju, Upendra
item WHITEHEAD, WAYNE - FORT VALLEY STATE UNIV
item SINGH, BHARAT - FORT VALLEY STATE UNIV
item WANG, SHIRLEY - FORT VALLEY STATE UNIV

Submitted to: European Journal of Agronomy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/7/2006
Publication Date: 7/27/2006
Citation: Sainju, U.M., Whitehead, W.F., Singh, B.P., Wang, S. 2006. Tillage, cover crops, and nitrogen fertilization effects on soil nitrogen and cotton and sorghum yields. European Journal of Agronomy. 25:372-382.

Interpretive Summary: Sustainable management practices, such as conservation tillage and cover cropping, which can increase soil organic matter and reduce soil erosion and nitrogen leaching, still remain a challenge for cotton and production systems. Conservation tillage increases the amount of crop residue left in the soil after harvest, which protects the surface soil from erosion, and increases soil organic matter, aggregation, water infiltration, and water holding capacity compared with conventional tillage. Similarly, cover crops cover soil during fallow periods, thereby reducing soil erosion and N leaching, improving soil organic matter, aggregation, and water holding capacity, and influencing crop yields compared with no cover crop. Use of conservation tillage and cover cropping provide opportunities to sustain crop yields and improve soil and water qualities in the southeast USA and in regions having mild winter which can support cover crop growth and where soil organic matter content is lower. The influence of three tillage practices (no-till, strip till, and chisel till ), four cover crops [legume (hairy vetch), nonlegume (rye), vetch and rye biculture, and winter weeds or no cover crop], and three N fertilization rates (0, 60 to 65, and 120 to 130 kg N ha-1) were examined on soil inorganic N content at the 0 to 30 cm depth and yields and N uptake of cotton and sorghum. The field experiment was conducted from 1999 to 2002 in Georgia, USA. Soil inorganic N content was higher in hairy vetch and hairy vetch/rye biculture than in rye or winter weeds. Cotton lint yield and lint N uptake were higher with rye or 60 kg N ha-1 than with vetch, biculture, and 120 kg N ha-1. In contrast, cotton biomass (stems + leaves) yield and N uptake were higher with vetch, biculture, and 60 kg N ha-1 than with rye, weeds, and 0 kg N ha-1. Sorghum grain and biomass yields and N uptake were higher with vetch, biculture and 120 kg N ha-1 than with rye, weeds and 0 kg N ha-1. Increased N supplied by hairy vetch or 120 to 130 kg N ha-1 increased soil N availability, sorghum grain yield, cotton and sorghum biomass yields, and N uptake but decreased cotton lint yield and lint N uptake compared with rye, weeds, or 0 kg N ha-1. Cotton and sorghum yields and N uptake can be optimized and potentials for soil erosion and N leaching can be reduced by using conservation tillage, such as no-till or strip till, with vetch and rye biculture cover crop and 60 to 65 kg N ha-1.

Technical Abstract: Sustainable soil and crop management practices that reduce soil erosion and nitrogen (N) leaching, conserve soil organic matter, and optimize cotton and sorghum yields still remain a challenge. We examined the influence of three tillage practices (no-till, strip till, and chisel till ), four cover crops {legume [hairy vetch (Vicia villosa Roth)], nonlegume [rye (Secaele cereale L.)], vetch/rye biculture, and winter weeds or no cover crop}, and three N fertilization rates (0, 60 to 65, and 120 to 130 kg N ha-1) on soil inorganic N content at the 0 to 30 cm depth and yields and N uptake of cotton (Gossypium hirsutum L.) and sorghum [Sorghum bicolor (L.) Moench]. A field experiment was conducted on Dothan sandy loam (fine-loamy, siliceous, thermic, Plinthic Paleudults) from 1999 to 2002 in Georgia, USA. Nitrogen supplied by cover crops was greater with vetch and vetch/rye biculture than with rye and weeds. Soil inorganic N at the 0 to 10 and 10 to 30 cm depths increased with increasing N rate and were greater with vetch than with rye and weeds in April 2000 and 2002. Inorganic N at 0 to 10 cm was also greater with vetch than with rye in no-till, greater with vetch/rye than with rye and weeds in strip till, and greater with vetch than with rye and weeds in chisel till. In 2000, cotton lint and N uptake were greater in no-till with rye or 60 kg N ha-1 than in other treatments, but biomass (stems + leaves) yield and N uptake were greater with vetch and vetch/rye than with rye or weeds, and greater with 60 and 120 than with 0 kg N ha-1. In 2001, sorghum grain, biomass yield, and N uptake were greater in strip till and chisel till than in no-till, and greater in vetch and vetch/rye with or without N than in rye and weeds with 0 or 65 kg N ha-1. In 2002, cotton lint yield and N uptake were greater in chisel till, rye, and weeds with 0 or 60 kg N ha-1 than in other treatments, but biomass N uptake was greater in vetch/rye with 60 kg N ha-1 than in rye and weeds with 0 or 60 kg N ha-1. Increased N supplied by hairy vetch or 120 to 130 kg N ha-1 increased soil N availability, sorghum grain yield, cotton and sorghum biomass yields, and N uptake but decreased cotton lint yield and lint N uptake compared with rye, weeds, or 0 kg N ha-1. Cotton and sorghum yields and N uptake can be optimized and potentials for soil erosion and N leaching can be reduced by using conservation tillage, such as no-till or strip till, with vetch/rye biculture cover crop and 60 to 65 kg N ha-1. The results can be applied in regions where cover crops can be grown in the winter to reduce soil erosion and N leaching and where tillage intensity and N fertilization rates can be minimized to reduce the costs of energy requirement for tillage and N fertilization while optimizing crop production.