Soil methane (CH4) fluxes in cropland with permanent pasture and riparian buffer strips with different vegetation(#)

Background Methane (CH4) has a global warming potential (GWP) 28 times that of carbon dioxide (CO2) over a 100-year horizon. Riparian buffers strips are widely implemented for their water quality protection functions along agricultural land, but conditions prevailing within them may increase the production of radiative greenhouse gases (GHGs), including CH4. However, a few information is available regarding the dynamics of unintended emissions of soil CH4 in these commonplace features of agroecosystems and how the dynamics compare with those for agricultural land. Aims To understand the dynamics of soil CH4 fluxes from a permanent upslope pasture and contiguous riparian buffer strips with different (grass, willow, and woodland) vegetation as well controls with no buffer vegetation, an experiment was carried out using the static chamber technique on a replicated plot-scale facility. Methods Gas fluxes were measured periodically with soil and environmental variables between June 2018 and February 2019 at North Wyke, UK. Results Soils under all treatments were sinks of soil CH4 with the willow riparian buffer (-2555 +/- 318.7 g CH4 ha(-1)) having the lowest soil CH4 flux followed by the grass riparian buffer (-2532 +/- 318.7 g CH4 ha(-1)), woodland riparian buffer (-2318.0 +/- 246.4 g CH4 ha(-1)), no-buffer control (-1938.0 +/- 374.4 g CH4 ha(-1)), and last, the upslope pasture (-1328.0 +/- 89.0 g CH4 ha(-1)), which had a higher flux. Conclusions The three vegetated riparian buffers were more substantial soil CH4 sinks, suggesting that they may help reduce soil CH4 fluxes into the atmosphere in similar agroecosystems.