Sustainable cropping systems for high rainfall areas of southwestern Australia

Abstract

Crop production has increased in the high rainfall (400–700 mm annual rainfall) areas of southwestern Australia in response to prolonged poor prices for wool relative to improvements in grain production technology and a desire by farmers to diversify their enterprise mix. The paper defines the higher rainfall region and suggests that approximately 70% of the area is potentially arable. Economic analysis indicates that for a range of grain and wool prices, profitability is maximised if 20–40% of the farm is cropped. So, cropping is likely to remain an important part of the farming system in this region. In southwestern Australia, water draining below the root zone causes saline groundwater to rise and leads to the development of dryland salinity. It is, therefore, important to develop cropping systems that minimise leakage of water past the root zone. The paper concludes that 30% of the farm needs to be in perennial pasture such as lucerne to minimise deep drainage. A rotation of 3 years of lucerne and 3 years of crop over 60% of the farm would meet this target and allow up to 30% of the farm to be cropped. The strategic introduction of trees in cropped areas increases the potential arable area that can be in crop without a rise of salinity. It is concluded that with careful arrangement of annual crops with perennial vegetation, sustainable crop production is achievable in the high rainfall areas of southwestern Australia.