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Soil Science Society of America Journal Abstract -

Modeling Potassium Uptake by Slash Pine Seedlings from Low-Potassium-Supplying Soils


This article in SSSAJ

  1. Vol. 54 No. 5, p. 1413-1421
    Received: June 26, 1989

    * Corresponding author(s):
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  1. K. C. J. Van Rees ,
  2. N. B. Comerford and
  3. W. W. McFee
  1. Dep. of Soil Science, Univ. of Saskatchewan, Saskatoon, SK S7N 0W0, Canada
    Soil Science Dep., 2169 McCarty Hall, Univ. of Florida, Gainesville, FL 32611
    Agronomy Dep., Lilly Hall of Life Sciences, Purdue Univ., West Lafayette, IN 47907



The application of diffusion/mass-flow theory to K uptake by slash pine (Pinus elliottii Engelm. var. elliottii) seedlings from low-K-supplying soils is presented. Simulations for K uptake were evaluated by the Barber-Cushman model (BCM) and the Baldwin-Nye-Tinker model (BNTM) under greenhouse and field conditions. Potassium uptake was overpredicted by 31 to 50% in greenhouse studies; overestimates, however, are attributed to nonuniform distribution of roots along pot walls. Simulations underpredicted K uptake by 0.48 and 0.83 times that observed in seedlings grown in the field. Although ectomycorrhizal hyphae were abundant in the field, their contribution to K uptake was not incorporated. Predictions of K uptake were excellent for seedlings grown at a tree nursery when fertilizer amendments were included. The BNTM, based on simplifying assumptions, predicted K-uptake values similar to the BCM. Sensitivity analysis showed that root growth and initial K concentration in soil solution were the two most important factors affecting K uptake by slash pine. Soil processes that control K concentration were the limiting factors to K uptake on these soils. Monte Carlo procedures indicated that, for two harvests in the field, simulated estimates of uptake had CVs ranging from 34 to 64%.

A contribution of the Florida Agric. Exp. Stn. Journal Series no. R-00001.

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