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This article in AJ

  1. Vol. 99 No. 3, p. 682-691
     
    Received: June 13, 2006


    * Corresponding author(s): usainju@sidney.ars.usda.gov
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doi:10.2134/agronj2006.0177

Accumulation and Crop Uptake of Soil Mineral Nitrogen as Influenced by Tillage, Cover Crops, and Nitrogen Fertilization

  1. Upendra M. Sainju *a,
  2. Bharat P. Singhb,
  3. Wayne F. Whiteheadb and
  4. Shirley Wangb
  1. a USDA-ARS-NPARL, 1500 North Central Ave., Sidney, MT 59270
    b Agricultural Research Station, Fort Valley State Univ., 1005 State University Dr., Fort Valley, GA 31030

Abstract

Management practices may influence soil N levels due to crop uptake and leaching. We evaluated the effects of three tillage practices [no-till (NT), strip till (ST), and chisel till (CT)], four cover crops [hairy vetch (Vicia villosa Roth), rye (Secale cereale L.), vetch + rye biculture, and winter weeds or no cover crop], and three N fertilization rates (0, 60–65, and 120–130 kg N ha−1) on NH4–N and NO3–N contents in Dothan sandy loam (fine-loamy, kaolinitic, thermic, Plinthic Paleudults), and N uptake by cotton (Gossypium hirsutum L.) and sorghum [Sorghum bicolor (L.) Moench] from 2000 to 2002 in central Georgia. Nitrogen content was higher in vetch and vetch + rye than in rye and weeds. Soil NH4–N content at 0 to 30 cm was higher at harvest than at planting, and higher in NT or vetch with 120 to 130 kg N ha−1 than with other treatments. The NO3–N content at 0 to 120 cm varied with date of sampling and was higher with vetch than with rye and weeds. The NO3–N content at 0 to 10 cm was higher in CT with vetch than in NT and ST with rye or weeds. From November 2000 to April 2001 and from November 2001 to April 2002, N loss from crop residue and soil at 0 to 120 cm was higher with vetch than with other cover crops. Nitrogen removed by cotton lint was higher with rye than with other cover crops in 2000 and higher with 0 and 60 than with 120 kg N ha−1 in 2002, but N removed by sorghum grain and cotton and sorghum biomass were higher with vetch than with rye, and higher with 120 to 130 than with 0 kg N ha−1 Because of higher N supply, vetch increased soil mineral N and cotton and sorghum N uptake compared with rye, but also increased the potential for N leaching. The potential for N leaching can be reduced and crop N uptake can be optimized by mixing vetch with rye.

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