Key Points
- The combined losses of N (leaching of nitrate, gaseous losses of ammonia, nitrogen and nitrous oxide) to the environment can be large. They represent a significant loss in economic efficiency of fertilisers (N-use efficiency) and have important impacts on groundwater quality and greenhouse emissions.
- Nitrification and urease inhibitors have potential to reduce nitrate (NO3-) leaching, and reduce emissions of ammonia (NH3) and the greenhouse gas nitrous oxide (N2O).
- Nitrification inhibitors restrict the microbial conversion of ammonium to nitrate and hence to the gases nitrogen and nitrous oxide in soil. The most common nitrification inhibitor is dicyandiamide (DCD). It is available in two proprietary products Eco-n and DCn.
- Urease inhibitors restrict the conversion of urea and urine to ammonium, and hence to nitrate in soils. Agrotain is the most common urease inhibitor and is available as SustaiN.
- Most research in New Zealand has been conducted with Eco-n on grazed dairy pasture where significant reductions in N losses and some gains in pasture production have been achieved.
- FAR is investigating whether any of these products have advantages in arable systems.