Regional-scale comparisons of greenhouse gas emissions from ditches and cropland soils 

Drainage and irrigation ditches are hotlines of greenhouse gas (GHG, including CH4, CO2, and N2O) emissions. These emissions are particularly high from agricultural ditches, due to inputs of organic and inorganic nutrients from land management. However, the total GHG emissions from agricultural ditches and their contribution to regional and national budgets remains largely unknown, due to a twin data gap of measured GHG fluxes and mapped ditch areas. Here, we estimated diffusive GHG emissions from agricultural ditches across the North China Plain (~141,000 km2), one of the most intensive agricultural regions worldwide, based on three regional-scale field campaigns on 36 ditch-river systems, each of which included collector ditches (CD), branch ditches (BD), main ditches (MD), and a connected river, in 2023. The results found that ditches emitted diffusive greenhouse gas emissions five times larger than their area share over the North China Plain.