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This article in AJ

  1. Vol. 91 No. 5, p. 753-760
    Received: Nov 30, 1998
    Published: Sept, 1999

    * Corresponding author(s): pwunger@ag.gov


Conversion of Conservation Reserve Program (CRP) Grassland for Dryland Crops in a Semiarid Region

  1. Paul W. Unger *a
  1.  aUSDA-ARS, Conservation and Production Res. Lab., P.O. Drawer 10, Bushland, TX 79012 USA


Information was needed regarding practices suitable for returning grassland to cropland when Conservation Reserve Program (CRP) contracts expired. A study on Pullman soil (Torrertic Paleustoll) involved seven tillage treatments (no-tillage and reduced, sweep, disk, moldboard plus disk, burn–sweep, and burn–disk tillage) with vegetation retained and the five non-burn tillage treatments with vegetation removed before treatment. Fertilizer (NH4NO3) was applied at 0, 34, and 67 kg N ha−1 in 1995 and at 0, 67, and 134 kg N ha−1 in 1996 and 1997. Initial soil water contents were low, and soil never was filled with water at planting time. Sorghum [Sorghum bicolor (L.) Moench] yielded ≤720 kg ha−1 in 1995, and the 1995–1996 wheat (Triticum aestivum L.) crop failed. Sorghum was not planted in 1996 because of a drought. Sorghum yielded 2260 to 4700 kg ha−1 in 1997. Wheat yielded 1410 to 1980 kg ha−1 in 1996–1997. Vegetation retention or removal affected yields slightly. Fertilization affected sorghum yields slightly and increased wheat yields. Vegetation control was difficult with no-tillage. Disk tillage to dislodge grass, followed by reduced- or no-tillage, appears best for converting CRP grassland to cropland in this semiarid region. Because of low initial soil water contents, a 90-d period is inadequate for obtaining adequate soil water storage unless precipitation is much above normal. Forgoing planting a crop soon after killing the vegetation when precipitation is low would provide more time for storing soil water and increase the potential for obtaining favorable yields.

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Copyright © 1999. American Society of AgronomySoil Science Society of America