Management strategies to minimise climatic risk to wheat production in low rainfall areas of southern Australia

Abstract

Much of the wheat produced in southern Australia is grown under rainfed agriculture where a lack of moisture limits crop production over the growing season, usually between April and October. The objectives of this investigation were (i) to assess climatic risk to wheat production, and (ii) to develop simple risk management principles in evaluating alternate strategies to increase and stabilise wheat yield in low rainfall areas of southern Australia. Annual rainfall analysis for eight selected sites in southern Australia (South Australia and Victoria) showed that generally rainfall is not declining at these sites. Thus, criteria developed for risk assessment and management based on historical climatic data can be useful to minimise risks to the farmers. The length and reliability of crop season were assessed by studying monthly rainfall and potential evaporation, weekly and daily rainfall, and simulated weekly soil water. The length of reliable cropping season was quite variable across locations. Wheat yields were simulated for average and well-managed conditions. Comparisons of simulated yields with experimental and farmers yields gave a good description of the gap between yields achieved by growers and potentially achievable yields, and the need for appropriate management practices to reduce the gap. A risk management strategy based on the amount of rainfall received between 1 April and 15 June (early season rainfall) was evaluated using historical rainfall and wheat yield data from Minnipa Research Centre. Results showed that the overall benefits in the past 30 years would have been substantially greater if sown area was increased in high early season rainfall years and reduced in low early season rainfall years.