EROSION PRODUCTIVITY MODELING OF MAIZE FARMING IN THE PHILIPPINE UPLANDS PART I - PARAMETERISING THE AGRICULTURAL PRODUCTION SYSTEMS SIMULATOR/

This paper describes the parameterisation of the Agricultural Producti on Systems Simulator (APSIM) model to simulate open-field farming and intercropping of maize with leguminous shrub hedgerows. Whenever possi ble, parameters for the model were determined from measured or standar d values for the environment of the field trials, while other paramete rs were derived from previous modelling experience in tropical environ ments. The remaining parameters were derived using step-wise calibrati on, where one or two parameters were calibrated against closely relate d measured data. Once parameterised, APSIM gave acceptable predictions of maize yields and soil loss from open-field farming and hedgerow in tercropping. The version of APSIM described in this paper is used to s imulate maize yields and soil erosion from open-field farming and hedg erow intercropping in the second paper in this series (Nelson et al., this issue). In the third paper, Nelson et al. (this issue) use cost-b enefit analysis to compare the economic viability of hedgerow intercro pping relative to traditional open-field farming of maize in relativel y inaccessible upland areas. (C) 1998 Elsevier Science Ltd. All rights reserved.