Improving reliability of maize production in marginal rainfall environments of the North East Region

Opportunities for expanded raingrown maize production in marginal rain:full areas (<600 mm annual rain:full) in north-eastern Australia have been studied experimentally and using crop modelling. These areas are characterised by high inter- and intra-seasonal variation in timing and amount of rainfall and periodic water stress. This study used APSIM-Maize to assess impacts of soil, climate and selected agronomic practices on predicted maize yield for early (late July-September) to late (January-February) planting in 7 day intervals, phenotypes (14, 16, 18, 20 and 22 leaves), initial :fraction of extractable water at planting (IFESW) (50, 65, 80 and 100%) of plant available water content, typical soils and plant population (1.2 to 4.2 plants m^-2) across 29 widely distributed locations in NE Australia using around 100 years of weather data. Risk to crop production was assessed in terms of :factors that contributed most to yield variability. Assessment of these :factors using a simple AN OVA model showed site, IFESW, plant population, planting date, phenotype, plant population x IFESW, site x planting date and soil within site to be the major contributors to variation in predicted yield. Here we present an approach to analysis of the yield predictions as a way of identifying similar sites where similar cultivar selection and agronomic practices would be appropriate.