Methane uptake rates across different soil types and agricultural management practices in Denmark

Abstract

Upland terrestrial soils play a crucial role in the global methane (CH4) cycle, although their potential as sinks for CH4 remains inadequately quantified. This study investigated CH4 uptake rates spanning two full years at four locations representing typical soil types and crop rotations in Denmark. The sampling campaigns included a total of more than 5000 manual static chamber flux measurements. All locations were, on average, small net sinks for CH4 while displaying significant differences between locations ranging from −1.5±0.3 g CH4-C ha−1 day−1 on the loamy soils to −3.8±0.3 g CH4-C ha−1 day−1 on the sandy soil with the lowest bulk density. A significant negative effect of soil moisture on CH4 uptake was also identified across the locations. Therefore, this study highlights the importance of soil texture and moisture as key controlling variables for CH4 uptake and emphasizes the need for local estimates of sink capacity. Overall, there were no detectable effects of agricultural management practices and fertilisation events did not affect the CH4 flux except for some high emissions following cattle slurry application on coarse sandy soil, which needs some consideration.