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

Abstract

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.

Keywords:

• ammonia
• farm effluent
• manure
• mitigation
• nitrous oxide

Acknowledgements

The authors gratefully acknowledge funding from Ballance Agri-Nutrients Limited and the New Zealand Government through the Livestock Emissions & Abatement Research Network (LEARN) scholarship programme. The authors also acknowledge funding for Taishan Scholars Programme for overseas experts. Any view or opinion expressed does not necessarily represent the view of the funding organisations.