Smart Blending of Enhanced Efficiency Fertilisers to Maximise Sugarcane Profitability. Final report to the Rural R&D for Profit Program - More Profit from Nitrogen

Abstract

Australian sugarcane farms receive about 60,000 tonnes of fertiliser nitrogen (N) each year. Nonetheless, only 35-70% of the applied N can be used by the crops or be retained in soil, with the remaining lost into deep ground, air and/or waterways. Nitrogenous fertiliser use on cane farms is the main source of anthropogenic dissolved inorganic N entering into the Great Barrier Reef waters, which poses a great threat to the natural balance of the reef ecosystems. Effective and efficient N management techniques are required to improve farming profitability whilst minimising the environmental impacts.

There has been increasing interest in Enhanced-Efficiency Fertilisers (EEFs) as a management strategy to improve fertiliser N use efficiency. For example, polymer-coated urea (PCU) can control N release after application into soil, thereby potentially better matching fertiliser N supply with plant N uptake. Another type of EEF is nitrification inhibitor-impregnated or -coated urea (NI+U). Nitrification inhibitors can reduce the accumulation of nitrate, which is susceptible to losses through leaching, runoff and/or denitrification. Numerous research trials have demonstrated that EEFs can improve fertiliser N use efficiency, reduce N loss and increase crop yield or maintain productivity at lower N application rates in various cropping systems worldwide including Australian sugarcane farms. However, EEFs are generally $120-600/t more expensive than normal urea and their agronomic and environmental benefits vary with soil, crop, weather and farming system management practices. The higher costs and efficacy variability are the main inhibitors to the adoption of EEFs.