Track 2-06: Greenhouse Gas Dynamics and Monitoring

Description

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.

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Effect of Soil Moisture Status and Animal Treading on N2O Emissions and the Effectiveness of a Nitrification Inhibitor Mitigation Technology

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.