APSIM features in international intercomparison of simulation models for grassland and crop yield and N2O emissions

In a paper recently accepted for publication in Global Change Biology (published open access), APSIM has contributed to an assessment of the ability of simulation models to simultaneously predict yield and N2O emissions.  The study included five variants of APSIM (two in the crop part of the study and three in the grasslands part).  In this study the modellers started with little site information (soil properties, weather data, management information) as Stage 1 and incrementally more data was supplied until in Stage 5 modellers had all available data.  Crop model outputs improved at Stage 3 when phenology information was made available but grassland model outputs were little affected by the availability of additional information.  As with other intercomparisons, the ensemble median performed better than any one model when considering multiple sites.  It was found that a small ensemble of three models outperformed the full ensemble.  This is the first study which has examined the effect of data availability of the performance of an ensemble and also the first examining both yield and N2O emissions.