The Agricultural Production Systems Simulator (APSIM) model was used to investigate the effects of 40 years of four land management practices. It was calibrated for local conditions using field measurements from 12 runoff plots at Katumani. The model was then validated using the data obtained from treatments conducted over nineteen cropping seasons. The model was initialised using the soil parameters obtained from virgin land, of similar soil type, adjacent to a newly opened farm at the Kathekakai Settlement Scheme.