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Soil Science Society of America Journal Abstract -

Crop Rotation and Tillage Effects on Phosphorus Distribution in the Central Great Plains


This article in SSSAJ

  1. Vol. 61 No. 5, p. 1418-1422
    Received: Sept 11, 1995

    * Corresponding author(s): rbowman@lamar.colostate.edu
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  1. R. A. Bowman  and
  2. A. D. Halvorson
  1. USDA-ARS, P.O. Box 400, 40335 City Road GG, Akron, CO 80720



The fate and availability of soil P in the central Great Plains may become less predictable with less tillage and more intensive crop rotations that produce more crop residue and litter than conventional-till (CT) wheat (Triticum aestivum L.)-fallow (W-F). We need to evaluate these new systems relative to new P distribution patterns that may be occurring. We determined P changes in a Weld silt loam soil (fine, montmorillonitic, mesic aridic Paleustoll) in predetermined plots from a 5-year rotation-tillage experiment where 45 kg P ha−1 was applied in 1990, and 18 kg P ha−1 was applied to the wheat phase of the rotation thereafter. We determined changes in water-soluble P, resin-extractable P, total organic P, bicarbonate-extractable P, and phosphomonoesterase activity as a function of tillage and cropping intensity in soil from the 0- to 5-cm and 0- to 15-cm depths. Phosphorus concentration in wheat tops at an early stage was also determined to assess soil P availability. Generally, P availability indices increased significantly in the 0- to 5-cm depth with continuous cropping treatments compared with wheat-fallow treatments. The results suggest that under more intensive cropping systems P recycling through residue and litter could be an important mechanism resulting in additional plant-available P.

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