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This article in SSSAJ

  1. Vol. 53 No. 1, p. 153-158
     
    Received: Mar 28, 1988


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doi:10.2136/sssaj1989.03615995005300010029x

Modeling Soil and Plant Phosphorus Dynamics in Calcareous and Highly Weathered Soils

  1. A. N. Sharpley ,
  2. U. Singh,
  3. G. Uehara and
  4. J. Kimble
  1. Dep. Agronomy, Oklahoma State Univ. and USDA-ARS, Water Quality and Watershed Research Laboratory, P.O. Box 1430, Durant, Oklahoma 74702-1430
    Dep. Agronomy and Soil Science, Univ. Hawaii, Honolulu, Hawaii 96822
    USDA-SCS-SMSS, National Soil Survey Lab., Lincoln, Nebraska 68508-3866

Abstract

Abstract

Labile and organic phosphorus (P) and sorbed P are required as the minimum data set to run a soil-plant P cycling model recently developed for continental U.S. soils. Labile and organic P and P sorption index were related to physical and chemical properties of 23 calcareous (>50 g kg−1 CaCO3 content) and 32 highly weathered soils (>30% Al saturation), to allow estimation of these P forms from readily available soil data. The P sorption or fertilizer availability index was estimated as the fraction of fertilizer P remaining as labile (resin extractable) P following incubation of soil and fertilizer. Labile P was linearly related (R2 = 0.71–0.90) to soil test P measured by Olsen (calcarous soils) and by Bray, Colwell, Mehlich III, and Truog methods (highly weathered soils). Organic P was also linearly related to organic C (R2 = 0.87) and total N (R2 = 0.89) content of all soils. Fertilizer P availability index decreased with increased incubation time from 30 to 180 d, with the decrease related to CaCO3 and extractable Fe and Al contents of calcareous and highly weathered soils, respectively. At the present time, the model uses a 180-d incubation value of fertilizer P availability index, which can be estimated from CaCO3 and clay contents of the calcareous and highly weathered soils, respectively. Using these relationships, accurate simulations were obtained of P transformations during 60-yr cultivation of calcareous Houston Black clay and yield of maize (Zea mays L.) on two highly weathered Hawaiian soils receiving varying amounts of fertilizer P.

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