Technologies to Mitigate Nitrous Oxide Emissions From Grazed Pastoral Agriculture.

New Zealand has always been at the forefront of climate change debate and one of the leading countries in agricultural greenhouse gas (GHG) research. The New Zealand agricultural sector contributes nearly 50% of all national GHG emissions. Of this, nitrous oxide (N2O) from pasture soil accounts for 34.2% and methane (CH4) from enteric fermentation accounts for 64% of CO2 equivalent emissions. About 84% and 13% of the N2O emissions are contributed by animal excreta and fertiliser input, respectively. . Globally, a range of effective technologies and management practices to mitigate GHG emissions are being devised, implemented and refined. For example, in the case of N2O we can identify three management levels that influence its emission and mitigation. The first is to influence soil nitrogen (N) transformations through managing N fertiliser and manures and effluent inputs by using nitrification inhibitors (NIs), optimising N application time and rates, and other soil management practices. This mitigation strategy is applicable to all agricultural production systems including cropping, horticulture, vegetable crops and pastoral farming. The second and third levels, applicable to livestock farming, focus on plant and animal management (stocking rate, choice of plant and animal type, time of grazing, enhanced animal productivity and low N in pastures), and animal feeding and system management (low N supplementary feed, controlled grazing, animal diet manipulation, etc.). Some of these technologies, such as the use of N transformation inhibitors, appropriate application of farm effluents, and stand-off pads are promising and are being adopted; others need further research and development before adoption. In New Zealand, there has been increasing interest in the use of nitrification (NI) and urease (UI) inhibitors (e.g., EcoN and SustaiN) to reduce N losses through N2O emission and NO3- leaching. This paper will describe the impacts of the application of N transformation inhibitors and farm effluents, and use of stand-off pads on N2O emissions reductions.