Predicting B Transport in Soils Using the UNSATCHEM Model.

Boron transport predictions are necessary for reclamation and management of high B soils and waters. The strong pH dependence of adsorption requires that predictive transport models have the capability to predict adsorption- and desorption as related to soil solution pH. Thus, the models require predictive routines for pH as well as adsorption. Characterization of the B adsorption as a function of pH for each soil is a time consuming process, and most transport models utilize simple K_d or Langmuir adsorption expressions, that do not provide adequate predictive capability. In this study we examine B transport in three arid land soils irrigated with waters with a range of pH values, first with and then without B. Prediction of B transport was made using the UNSATCHEM model incorporating the model developed by Goldberg et al. 2000 for generation of constant capacitance model parameters based on soil properties without any input of soil specific B adsorption measurements or calibration. Model predictions simulated the pH dependence of B transport and provided satisfactory correspondence with experimental results.