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

To obtain accurate N 2 O and CH 4 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 N 2 O and CH 4 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. N 2 O was emitted during spring-thaw and post-fertilizer application periods for cropped positions and CH 4 was emitted about 7 wk after soil thaw for lower and riparian elements. While there was no statististical difference in N 2 O emission from upper, middle and lower landscape elements, there was greater occurrence of N 2 O emission hotspots at the lower element, associated with its comparatively higher soil moisture and carbon availability. A location of intense CH 4 emission in a riparian area had considerably less soil sulfate compared with other riparian locations. We conclude that hotspots for N 2 O and CH 4 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 N 2 O and CH 4 emissions are lower and higher, respectively. Riparian areas having high sulfate concentrations do not seem to emit appreciable amounts of CH 4 .Key words: Greenhouse gas emission, landscape element, landscape variability, methane, nitrous oxide, Prairie Pothole Region, sulfate