Nitrogen gaseous emissions from farm effluent application to pastures and mitigation measures to reduce the emissions: a review

Potential losses of nitrogen (N) from land application of effluents include ammonia (NH3) and nitrous oxide (N2O) emissions. In this review paper, the extent of the NH3 and N2O losses resulting from application of effluents to pastoral soils is assessed. Nitrogen losses, as NH3 and N2O, from applied effluent to pastoral soil ranged from 1%–66% and <0.1%–6% of the applied N, respectively. The potential mitigation methods include: reducing livestock numbers; lowering N content of the effluent; using N process inhibitors; optimising timing of effluent application; and applying effluent at rates that match plant uptake. It is important to remember that some of these options can result in ‘pollution swapping’ and some of them are in the early stages of development. Future research needs to focus on the overall impact of mitigation options on the whole suite of gaseous emissions and the practicality of those options.