Collection and automation of large undisturbed soil cores for laboratory leaching studies

A procedure for examining water and solute transport in large undisturbed s oil cores is described and tested. The procedure involves three main steps: (I)collecting soil cores using a "pushing method", (2) attaching a tension drainage system once soil cores are transported to the laboratory, and (3) inserting tensiometers and thetaprobes for continuous monitoring of soil w ater tension and soil water content before, during and after, water and sol ute application. This procedure allows accurate recording of the soil hydra ulic properties over the entire experiment, and provides valuable informati on for developing and running mathematical simulation models. Application o f the outlined procedure to solute leaching is demonstrated for a well-stru ctured Oxisol. Results from the laboratory leaching study are compared with theoretical predictions using a simple analytical model for weakly-sorbed ions. Contrasting behaviour between the model predictions and the experimen tal data is attributed to ion adsorption by the soil colloids.