Effect of soil moisture status and animal treading on N₂O emissions and the effectiveness of a nitrification inhibitor mitigation technology

Abstract

Nitrous oxide (N₂O) is a potent greenhouse gas with a long term global warming potential about 298 times that of carbon dioxide (CO₂). In grazed grassland, most of the N₂O is emitted from nitrogen (N) excreted by the grazing animal, particularly in the animal urine. When the soil is wet, such as that in winter grazing conditions, animal grazing can cause soil structural damage, leading to soil compaction. The combination of a wet soil plus soil compaction is particularly conducive for N₂O production. A nitrification inhibitor technology using dicyandiamide (DCD) has been developed to reduce N₂O emissions from grazed grassland (Di and Cameron 2002; 2003). However, the efficacy of this technology under wet and compact soil conditions has not been well studied. The objectives of this study were to determine: (1) The impact of soil moisture content on the abundance of ammonia oxidizers and N₂O emissions; (2) the impact of animal treading on N₂O emissions; and (3) The effectiveness of the nitrification inhibitor DCD in reducing N₂O emissions, as affected by soil moisture status and animal treading.