Greenhouse Gas Emissions from Agricultural Ditches in the North China Plain

Agricultural ditches are pervasive in agricultural areas and are potential greenhouse gas (GHG) hotspots, since they directly receive abundant nutrients from neighboring farmlands. However, few studies measure GHG concentrations or fluxes in this particular waterbody, likely resulting in underestimations of GHG emissions from agricultural regions. Here we conducted seasonal field studies to investigate the GHG concentrations and fluxes from agricultural ditch systems in the North China Plain. The results showed that almost all the ditches were large GHG sources, and their concentration were higher than that in the rivers connecting to the ditch systems. Nutrient input was the primary driver stimulating GHG production and emissions, resulting in GHG concentrations and fluxes increasing from rivers to collector ditches as the ditch systems approached farmlands and potentially received more nutrients. Overall, this study demonstrated that agricultural ditches were hotspots of GHG emissions, and future GHG estimations should incorporate this ubiquitous but underrepresented waterbody.