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This article in SSSAJ

  1. Vol. 54 No. 1, p. 193-198
     
    Received: May 5, 1989


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doi:10.2136/sssaj1990.03615995005400010030x

Cropping Frequencies to Sustain Long-Term Conservation Tillage Systems

  1. G. W. Langdale ,
  2. R. R. Bruce and
  3. R. L. Wilson
  1. USDA-ARS, Southern Piedmont Conservation Research Center, Watkinsville, GA 30677
    USDA-ARS, Russell Research Center, Athens, GA 30613

Abstract

Abstract

Conservation tillage technologies are essential to develop long-term alternative agriculture approaches to protect the nation's resources. This study was conducted to develop long-term multiple cropping systems to sustain conservation crop production. Soybean [Glycine max (L.) Merrill] and grain sorghum [Sorghum bicolor (L.) Moench] cropping sequences following wheat (Triticum aestivum (L.) grain harvest were studied at three tillage-intensity levels on a Cecil sandy loam (clayey, kaolinitic, thermic Typic Hapludult) soil. During the first 4-yr crop rotation cycle, coulter in-row chisel (MT) planted grain sorghum produced significantly more grain than either coulter (NT) or disk harrow (CT) planted (4.89 vs. 4.58 and 4.39 Mg ha−1), without a crop-rotation response. In the second 4-yr cycle, the sorghum grain yields declined NT > MT > CT (5.14 > 4.74 > 4.40 Mg ha−1) significantly with each increase in tillage-intensity level. Soybean responded consistently and significantly to high-frequency (1:1) rotation with grain sorghum. These responses to rotation with grain sorghum become less important to conservation tillage systems when favorable rainfall distributions permit grain yields that range between 2.00 and 3.50 Mg ha−1. Wheat yields increased significantly following soybean (first rotation cycle) until take-all (Graeumannomyces graminis) became epidemic. Elucidation of significant grain sorghum responses to in-row chisel and coulter conservation tillage during the first and second crop-rotation cycles, respectively, requires additional research that focuses on characterization of temporal changes in the soil environment. Rotation of both cool- and warm-season crops is necessary to sustain long-term conservation tillage.

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