Nitrous Oxide Emissions From Irrigated Versus Dryland Cropping Systems in the Semi-Arid Prairie.

Irrigated agriculture in Canada is poised to play a more prominent in response to increasing global food demands. Within the Canadian Prairies in particular, there is the potential to see large increases in the number of irrigated hectares, provided that existing water supplies are proven reliable and that the economic and environmental sustainability can be assured. With respect to greenhouse-gas-related atmospheric warming potential, the enhanced productivity of irrigated lands can potentially sequester greater amounts of carbon relative to dryland systems. However, these gains are partially offset by higher CO₂ emissions associated with energy used for pumping water, and increased N₂O emissions due to higher moisture content, and greater rates of N fertilization. This project is examining greenhouse gas emissions under irrigated conditions typical of the semi-arid prairies to identify how increased levels of soil moisture and fertility associated with irrigated systems influence N₂O emissions. A study of field-scale emissions from adjacent irrigated and dryland fields examines the processes driving greenhouse gas emissions, while a plot-scale study specifically examines the effect of N-fertilization practices and irrigated crop rotation sequence on emissions. The combined efforts will permit new N₂O emissions coefficients to be derived and will identify specific water, cropping, and fertilizer management strategies which can be used to minimize N₂O emissions under these systems.