Economic and environmental impacts of increased nitrogen use in grazed pastures and role of inhibitors in mitigating nitrogen losses

Addition of nitrogen (N) to soils not only increases plant productivity but also results in increased nitrate (NO3 –) leaching and release of gaseous N such as ammonia (NH3) and nitrous oxide (N2O). Recent sharp increases in fertiliser N inputs to grazed pastures in New Zealand have rekindled the debate on its impact on atmospheric, terrestrial and aquatic environments. There has been increasing interest in the use of inhibitors to mitigate environmental impacts of N losses from animal excreta and effluent application through leaching and gaseous emissions. This article gives an overview of the environmental impacts of N losses, discusses the role of inhibitors in mitigating N losses, and identifies gaps and limitations from existing New Zealand information. It also suggests the main research needed for devising mitigation strategies with inhibitors.