CC0210. Nitrous oxide release from excreta of grazing animals.
Nitrous oxide (N2O) is a major contributor to global warming effects due to its capacity to absorb long wave radiation. The main process responsible for N2O generation is denitrification of excess nitrate, particularly in intensively managed agricultural soils, and denitrification rates are relatively high in grazed grasslands, due to accumulations of nitrate derived from excreta. Therefore, it is suspected that grassland soils with excreta from grazing animals may be an important source of N2O. Measurement of N2O production from these grazed systems would assist in the construction of accurate overall budgets of N2O emissions and long term predictions of the effects of climate change. This study will aim to provide initial estimates of N2O fluxes from urine and dung patches. Initial field measurements will be obtained from such sites on poorly- and well-drained soils; 8 different treatments (excretal type timing) will be examined and environmental parameters will be monitored, including temperature, rainfall and soil moisture. The impact of dung and urine will also be investigated on N2O emissions from soils under controlled conditions, using different excretal types, soils, moisture contents and temperatures. It is anticipated that information from this project will contribute both to construction of N2O budgets and to understanding of N flows in grassland systems.