Approaches to Managing Variability of Rice Growth and Yield- Link (March 2013)

Beecher, G Dunn, B


This RIRDC report is aimed at rice growers, commercial and public advisory agronomists, rice researchers, irrigation surveyors and designers, and landforming operators in rice growing areas. The report outlines investigations into the causes of in-field variability of rice crop growth, yield and management options for improving the poor yielding areas. The project consisted of three main objectives including firstly identify and understand factors contributing to in-field spatial variability in rice yield. Secondly identify and evaluate methods by which rice growers can manage in-field spatial variability in yield to increase production, profitability and water productivity and thirdly to maintain the NIR calibrations and instruments for the rice NIR Tissue Testing Service and update the associated PI nitrogen topdressing recommendations. The project was undertaken using replicated field experiments which were located in multiple rice growers’ fields in areas of both natural soil (no cut or fill) and subsoil surfaces which had been exposed by laser levelling operations. Soil treatments consisted of both chemical fertiliser (with varying major and minor nutrients) and organic fertilisers (chicken litter and feedlot manure). Rice establishment, growth and yield were monitored and measured. Generally three sets of field experiments were implemented each season. In conjunction with this experiment each year of the project there were complementary extensive large pot experiments undertaken in a polyhouse at Yanco Agricultural Institute The research identified that most of the in-field variability in rice growth and yield variability could be attributed to poor growth and low yield being obtained on exposed sub-soil surfaces due to macro and micro nutrient deficiencies and interactions. Significant increase in rice crop growth and yield were obtained by applications of high rates of nitrogen and phosphorus fertilisers to exposed subsoils. Rice crop growth and yield responses were also were found on red brown earth soils with the application of zinc, either in the fertiliser mix sown with the seed or as a seed coat. The researchers believe that targeted applications (based on soil tests) of phosphorus and zinc, along with good pre-permanent water and PI nitrogen management will increase yields in exposed subsoil areas of rice fields. This will decrease in-field rice yield variability resulting in increased rice production and water productivity across the industry and provide flow-on economic benefits to regional communities.