Zvi Hochman1, Airong Zhang2, Marta Monjardino3, Heidi Horan1
1 CSIRO Agriculture and Food, Queensland Bioscience Precinct, 306 Carmody Road St Lucia QLD 4067, Australia
2 CSIRO Health and Biosecurity, EcoSciences Precinct, GPO Box 2583, QLD 4001, Australia
3 CSIRO Agriculture and Food, CSIRO Waite Campus, Waite Road, Urrbrae SA 5064, Australia
Why do Australian grain growers achieve only half the yield potential of their crops? We took three approaches to investigate this question. First, we applied in silico experimentation to quantify the impact of eight suboptimal practices at 50 sites across the grain zone. This analysis highlighted the critical importance of nitrogen nutrition. Other management-related factors included: conventional tillage, summer weeds, low seedling density and late sowing. Second, we interviewed 232 wheat producers from 14 contrasting local areas. The findings linked yield gaps to farm and grower characteristics as well as to farming management. Farms with smaller yield gaps are more likely to be smaller holdings growing less wheat on more favourable soil types. Growers with smaller yield gaps are more likely to apply more N fertiliser, to have a greater crop diversity and to be less likely to grow wheat following either cereal crops or a pasture; they are more likely to soil-test a greater proportion of their fields, use a fee-for-service agronomist, have a university education and adopt new technologies, and they are less likely to have problems with herbicide-resistant weeds. Third, we applied a profit-risk-utility trade-off analysis and showed that risk aversion has a strong influence on the choice of practice in low yield potential sites, which help explain yield gaps in those agro-climatic zones. However, in medium to high yielding areas, applying the management inputs required to achieve water-limited yield is the most economical choice even for highly risk averse growers.