Pattern of greenhouse gas emission from a Prairie Pothole agricultural landscape in Manitoba, Canada

Abstract

To obtain accurate N2O and CH4 emission estimates from the Prairie Pothole Region of North America, knowledge of landscape pattern and soil factors is important. A field study was conducted investigating the temporal and spatial variation in N2O and CH4 emissions from spring to fall 2005 and spring-thaw to post-fertilizer application period 2006 using static-vented chambers located at upper, middle and lower landscape elements planted to spring wheat in 2005 and flax in 2006 and riparian areas in an undulating terrain in southern Manitoba. N2O was emitted during spring-thaw and post-fertilizer application periods for cropped positions and CH4 was emitted about 7 wk after soil thaw for lower and riparian elements. While there was no statististical difference in N2O emission from upper, middle and lower landscape elements, there was greater occurrence of N2O emission hotspots at the lower element, associated with its comparatively higher soil moisture and carbon availability. A location of intense CH4 emission in a riparian area had considerably less soil sulfate compared with other riparian locations. We conclude that hotspots for N2O and CH4 emission within the landscape are localized and driven by high soil moisture and C availability, and riparian areas should be identified separately from cropped areas, as their N2O and CH4 emissions are lower and higher, respectively. Riparian areas having high sulfate concentrations do not seem to emit appreciable amounts of CH4.Key words: Greenhouse gas emission, landscape element, landscape variability, methane, nitrous oxide, Prairie Pothole Region, sulfate