AN AMENDED FUNCTIONAL LEACHING MODEL APPLICABLE TO STRUCTURED SOILS .1. MODEL DESCRIPTION

A functional model designed to simulate the transport of non-interacti ve solutes through macroporous soil is described. The concept of mobil e and immobile water is used but the pore volume available for mobile water is partitioned to allow for flow through smaller water-filled po res and rapid preferential flow through larger macropores and fissures . The general performance of the model under steady infiltration follo wing an injection of solute is presented. The sensitivity of the outpu t to variations in the model parameters is also discussed. A second pa per compares the model with bromide and chloride leaching data on two texturally contrasting soils.