Use of SCRUM-APSIM to predict soil water and soil nitrogen dynamics in arable crop rotations

Abstract

: Nitrogen (N) lost from agricultural fields to surface and groundwater systems is an important environmental problem. There is growing research interest in N management strategies to improve the sustainability of farming systems. Monitoring N balance in agricultural field is technically difficult and is complicated by differences in soil types, crops, and variability between and within seasons. Simulation modelling is an alternative approach that provides a way to evaluate mitigation options across a range of management and growing conditions. To serve as a reliable basis for nutrient management, prediction accuracy of simulations models needs to be demonstrated. This study evaluated the Simple Crop Resource Uptake Model operating within the Agricultural Production Systems sIMulator framework (SCRUM-APSIM) against field data for yield, N balance components (N uptake, soil mineral N and leaching) and soil water. Evaluation data were from a wheat-broccoli-onion crop rotation subjected to two irrigation rates (recommended and excessive) and four fertiliser N rates (N0, N1, N2, N3). No fertiliser was applied in N0, while N2 represented the recommended rate for each crop. N1 and N3 represented half and twice the rate of N2, respectively. Broccoli and onion crops were evaluated across all four fertiliser rates while a flat rate of 150 kg N/ha was applied to wheat irrespective of fertiliser N treatment. SCRUM-APSIM satisfactorily simulated crop rotations and managements as indicated by performance indices: