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This article in SSSAJ

  1. Vol. 51 No. 6, p. 1604-1610
    Received: Oct 14, 1986

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Soil-water Regimes of a Typic Haplaquoll under Conventional and No-tillage

  1. J. L. B. Culley,
  2. W. E. Larson,
  3. R. R. Allmaras and
  4. M. J. Shaffer2



Computer simulation models are needed to help describe the dynamic nature of soil-water regimes. A simple water budget and an integrated soil-plant-atmosphere simulation model (NTRM) were each evaluated for predicting water regimes under no-till (NT) and conventional tillage (CN) of a well-structured soil. Estimates of soil physical properties related to the retention and movement of water, which were required as input for the models, were obtained from laboratory measurements on undisturbed soil cores. An in situ drainage experiment, using Br- labeled water, also provided information on field capacity water retention properties. Ponded water containing Br- moved rapidly through the surface 0.5-m profiles of both tillage treatments. Redistribution of the added water was effectively completed within about 8 h. Field capacity matric potentials of both profiles were above −6 kPa. Chromatography theory indicated that the labeled water may have mixed with only 43 and 25% of the initial soil water in the CN and NT profiles, respectively. Despite these observations, both models, which assumed complete mixing within each soil layer, were reasonably satisfactory at predicting soil-water contents under corn (Zea mays L.) through the 1984 growing season at a southern Minnesota location. Output from the NTRM model agreed better with experimental data showing water contents lower under CN than NT.

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