Greenhouse gas emissions from cultivated and abandoned organic croplands in Finland

Human activities have enhanced the emissions of carbon dioxide (CO 2) and nitrous oxide (N2O) from organic soils. Drained peat soils may turn into a source of CO2 and N2O, whereas CH4 emission may generally decrease after drainage. Agricultural use, including ploughing, fertilization and irrigation, further enhances the decomposition of peat, and CO2 and N2O emissions. Cultivated organic soils are therefore significant sources of CO2 and N2O. In this paper we report greenhouse gas emissions from cultivated organic soils, and from abandoned organic agricultural soils, i.e. from organic soils where cultivation practices have ceased. We found that CO2 and N2O emissions from abandoned organic cropland soils do not generally decrease with time after agricultural practices have ceased, whereas CH4 fluxes from the atmosphere into the soil may gradually increase after leaving cultivation.