Enhanced Efficiency Fertilizers (EEF) for Agricultural Sustainability and Environmental Quality in Australia.

Increasing demand for food and fibre has led to an increase in fertilizer N use worldwide. In Australia in 2002, 972 Gg of fertilizer N was used with the majority applied to cereals. However, nitrogen fertilizer efficiency is low, for example wheat plants assimilate only around 40% of applied nitrogen. Losses of nitrogen can have both an economic and environmental impact. Australian agriculture is the greatest contributor to the total national emissions of the greenhouse gas (GHG) N₂O, and there is increasing interest in the role of nitrogen fertilisers in these emissions. Improvements in the efficiency of fertilizer nitrogen can be achieved through changes in land management practices, but even the best management practices cannot reduce all nitrogen loss pathways in all situations. Enhanced efficiency nitrogen fertilizers (EEF), such as controlled release products, and urease and nitrification inhibitors show promise in improving the efficiency of applied nitrogen and reducing the GHG emissions. The paper reports the current laboratory and field studies in Australia on the impacts of EEF on soil N dynamics and GHG emissions on rainfed wheat, irrigated pastures and sugarcane.

 Incubation studies showed that ESN (polymer coated urea) and Meister (polyolefin coated urea) were very effective in minimizing ammonia (NH₃) volatilization and reducing N_2­O emissions on a vertsosol cropped to wheat. The urease inhibitor, NBPT, was effective in reducing the NH₃ emission on both wheat and sugarcane soils, by 54% for sugarcane and 74% for wheat. The nitrification inhibitors, N-serve, dicyandiamide (DCD) and DMPP were very effective (up to 80%) in reducing the N₂O emissions in wheat, pasture and sugarcane.