CSIRO Agriculture and Food, GPO Box 1700, Canberra ACT 2601, Australia
The value of simulation models to assist (i) crop breeding, (ii) agronomic research, and (iii) farm decision-making has been demonstrated in many studies (Holzworth et al. 2014; van Ittersum and Donatelli 2003). In the Australian grains industry several modelling platforms have been developed for a variety of needs, with APSIM (Agricultural Production Systems Simulator) the predominant tool (Robertson et al. 2015). APSIM allows models of crop and pasture production, residue decomposition, soil water and nutrient flow, and erosion to be configured to simulate soil and crop management for various production systems using conditional rules (Holzworth et al. 2014). The model has been well validated in many studies and shown to accurately capture the effects of variability in climate, soil type and management for a range of crops. Linking of APSIM and GRAZPLAN farming systems models (Moore et al. 2007) has also enabled assessment of whole farm issues associated with crop and animal production as well as environmental impacts of a range of practices on mixed farms (Lilley and Moore 2009, Robertson et al. 2009).
In this paper I discuss application of the APSIM model at three scales; (i) the value of individual genetic traits within the context of the farming system, (ii) single or multiple changes to management practices for individual crops over multiple years and locations, and (iii) the effect of a management or genotype change, in the context of multi-year sequences, or multiple paddocks across the whole farm. Case studies at each scale will demonstrate the value of simulation modelling as an integrated tool in modern farming systems research.