Modelling farming systems performance at catchment and regional scales to support natural resource management.

Agricultural systems are multifunctional ecosystems that besides food production also provides ecosystem services. Agricultural system management is a major component of natural resource management (NRM). Farming systems modelling has been successfully used to develop understanding of soil–plant–climate interactions and to assist on-farm decision-making processes. There is an increasing demand for applying farming systems models beyond point/field scales to support NRM planning and decision-making in spite of the limitations of such models. This paper presents two case studies in south-east Australia on modelling farming systems performance beyond point/field scales to support NRM planning. The first study focuses on the impact of spatially explicit crop/vegetation management on catchment hydrology to address dryland salinity. A one-dimensional farming systems model was directly coupled with a catchment hydrology framework that deals with lateral water flow between spatially distributed land units. The second study assesses the impact of climate change on the productivity and water balance of farming systems across the Lower Murray Region in southern Australia to provide inputs into regional NRM planning. A process of derivation of soil data and development of spatial modelling zones was used to simplify the spatial modelling process. The limitations of scaling up the model approaches adopted are discussed.