Enhanced nitrogen fertiliser technologies support the '4R' concept to optimise crop production and minimise environmental losses

Fertiliser nitrogen (N) has been, and will continue to be, essential in nourishing, clothing and providing bioenergy for the human family. Yet, emissions of ammonia (NH3) and nitrous oxide (N2O), and losses of nitrate-N (NO3-N) to surface and groundwater resources are risks associated with fertiliser N use that must be better managed to help meet expanding societal expectations. Nitrogen fertilisers with polymer coatings, or with the addition of urease and/or nitrification inhibitors, or those possessing other characteristics that afford them either improved agronomic response and/or lessened loss of N to the environment (compared with a reference water-soluble fertiliser) may be considered enhanced-efficiency N fertilisers (EEFs). Agronomic and horticultural research with these technologies has been performed for many decades, but it has been primarily in the past decade that research has increasingly also measured their efficacy in reducing N losses via volatilisation, leaching, drainage, run-off and denitrification. Expanded use of EEFs, within the '4R' concept (right source, right rate, right time, right place) of N management may help increase crop yields while minimising environmental N losses. Coupling these 4R N management tools with precision technologies, information systems, crop growth and N utilisation and transformation models, especially weather models, may improve opportunities for refined N management in the future.