AN AMENDED FUNCTIONAL LEACHING MODEL APPLICABLE TO STRUCTURED SOILS .2. MODEL APPLICATION

The performance of a functional leaching model (Hall, 1993) is compared with leaching data from two lysimeter experiments with soils of contrasting texture using sodium bromide and potassium chloride as the non-reactive solutes. The model parameters are optimized using the solute elution curves as standards and compared with the physical properties of the soil. A good match with the measured discharge of both water and solute was achieved for both soils using the moisture release characteristics to define the pore volume available for mobile and immobile water. The results indicate that preferential flow takes place through even coarse-textured soils but that there is negligible diffusive exchange of solute between water passing through the macropores and the rest of the soil.