High rainfall zone grains: yield gaps, production trends and opportunities for improvement

There is growing recognition of the potential to increase crop production in the higher rainfall zones (HRZ) of southern Australia. We combined a survey of agricultural consultants, and an analysis of crop yields in order to (1) investigate recent trends in crop production, (2) quantify the gap between potential and actual crop yields, and (3) consider the factors thought to limit on-farm yields. The survey of agricultural consultants revealed that in the last 10 years there is a trend towards more cropping, an increased use of canola, adoption of dual purpose crops, and advances in the adaptation of cultivars to the HRZ. In Victoria, NSW and South Australia the long-term water-limited potential yield, estimated by modelling, consultants and experimental measurements, for HRZ wheat and canola was 5-6 and 2-3 t/ha for a decile 5 season. The equivalent values for WA were 4-5 and 2-3 t/ha, where yields were less responsive to good seasons than in the other states. There was a large gap between APSIM simulated potential yield and farmer-realised yields, however the top performing farmers were achieving close to the water-limited potential yield. In all regions, there appears to be scope for large gains in yield and productivity benefits by encouraging the below-average cropping farmers to adopt the practices and behaviours of the above-average farmers, such as being prepared to pay for inputs, more timely sowing, weed and disease control, and N-topdressing.