Seasonal and annual distribution of carbon, water and energy fluxes of irrigated agroecosystems in inland Australia

The extent to which agroecosystems contribute to the carbon cycle as net sources or sinks of atmospheric carbon dioxide remains relatively uncertain and it appears that in-depth studies of integrated water, carbon and energy fluxes of irrigated broad-acre crops for common Australian conditions and soil types are yet to be reported. Therefore, this study focuses on the use of eddy covariance methodologies to determine the empirical relationship between these fluxes for three of the major irrigated crops grown in inland Australia; maize, rice and wheat. Here we present the uptake or release of carbon dioxide in relation to evapotranspiration at different phenological stages for each crop at the field scale; and the extrapolation of these to provide an estimate of fluxes at the regional scale based on similar soil types. The annual distribution of the mass and energy exchange was also determined and the level of similarities and key differences between the carbon fluxes and energy partitioning under these particular climatic conditions were compared to similar studies of irrigated broad-acre agriculture production conducted elsewhere in the world.