APSfarm: A new framework for modelling mixed cropping and grazing farm businesses

Abstract

The long-term viability of mixed grain and graze farm businesses relies on having a diverse mix of enterprises with both pasture and cropping systems. Identifying the mix of enterprises and allocation of resources that maximise profitability needs better integrative and interdisciplinary modelling tools. In Australia, farm managers continuously fine tune tactics and strategies to keep their farm business profitable over time. Present climate variability, the cost-price squeeze, and the possible inclusion of agriculture in the Australian Emissions Trading Scheme by 2015, will require that agriculture in general, and graziers in particular, design short and long-term adaptation strategies. In this paper we describe the development of APSFarm, a more integrative and interdisciplinary whole-farm systems model and its application in a participatory research framework to identify more resilient designs of a mixed grain and graze farm business. In this study, APSFarm was used to model a mixed cropping and grazing farm in central Queensland that is opportunistic and responsive to the highly variable climate and to prices. The whole-farm simulation of different soils, cropping and grazing systems, provides production indices and environmental impacts of the farming system. We used APSFarm to compare current management practices with two alternative strategies: (i) increased land area and resources for the cropping enterprises, thereby decreasing the grazing enterprise; and (ii) increased area and resources for the grazing enterprises. These alternative strategies were evaluated in terms of trade-offs between profit and environmental outputs. These help us identify strategies that better cope with the variability in climate and prices. Results indicate that returns from a farm with a significant livestock enterprise had lower average returns but encountered lower extremes of returns. From the scenario studied, a farmer who is more averse to risk may choose to increase grazing area which may reduce downside risk especially during dry periods, and have little effect on average returns. Whilst there is a larger variation in income from cropping, there is the potential to make more money. There are tradeoffs of this practice change on environmental impacts with simulations showing that changing paddocks from annual cropping to perennial pasture reduced runoff by 25%, drainage by 65% and soil loss by 50%. In discussions with participating farmers, additional work would be required to identify optimum crop and pasture choices, changes in land use, and the expected impacts from long-term changes in climate and mitigation policy. We conclude that the use of integrative and interdisciplinary modelling tools such as APSFarm, can assist farmers make better decisions by having better informed discussions in relation to the management and design of complicated mixed grain and grazing systems.