Precision agriculture improves efficiency of nitrogen use and minimises its leaching at within-field to farm scales

We used precision agriculture techniques and the APSIM model for crop growth, water balance and nitrate leaching as a tool to monitor and improve the environmental and financial performance of farms at within-field resolution. We used yield maps, soil and climate data for two farms in Western Australia to determine spatial and temporal patterns of grain yield, drainage and nitrate leaching under a range of climatic, soil and management scenarios. On one farm, we up-scaled APSIM using soil type polygons and on another we used relationships between EM38 and soil water storage properties to map predicted yield and nitrate leaching and identify areas at greatest financial and environmental risks for management interventions.