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Soil Science Society of America Journal Abstract -

Model Comparison of Unsaturated Steady-State Solute Transport in a Field Plot


This article in SSSAJ

  1. Vol. 58 No. 5, p. 1277-1287
    Received: June 28, 1993

    * Corresponding author(s): knighton@badlands.nodak.edu
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  1. Jose Luis Costa,
  2. R. E. Knighton  and
  3. Lyle Prunty
  1. Estacion Experimental Agropecuaria, INTA, Balcarce, Argentina
    Dep. of Soil Science, North Dakota State Univ., Fargo, ND 58105



Models of solute movement in soil are seldom compared using independently generated data. The objectives of this study were to leach Br through a Hecla fine sandy loam (sandy, mixed Aquic Haploboroll) and to compare the results with four previously published solute transport models. Solute was applied over the surface of four 9-m2 subplots within a 65.5-m2 plot and leached at constant rates: 1.28, 2.53, 4.28, and 5.94 µm s−1. Soil solution samples were taken from 0.3-, 0.6-, 1.0-, 1.5-, 2.0-, 2.3-, and 2.5-m depths. At the same depths, water content and soil suction were measured using a neutron probe and tensiometers. Data from this experiment were used to evaluate four solute transport models. Model performance was evaluated using the observed to expected sum-of-squares ratio, the normalized objective function, and the Kolmogorov-Smirnov statistic. A numerical finite-difference solution of the convective-dispersive equation (LEACHM) was more successful in predicting solute movement under unsaturated steady-state conditions than the analytical solution for the convective-dispersive equation (CDE), the continuous-time Markov process (CTMP), or the transfer function model (TFM). The CTMP model predicts observed solute concentration better than the TFM. The TFM needs to be calibrated by a solute transport experiment while CTMP requires water flow and soil moisture as input data.

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