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 (N 2 O) from organic soils. Drained peat soils may turn into a source of CO 2 and N 2 O, whereas CH 4 emission may generally decrease after drainage. Agricultural use, including ploughing, fertilization and irrigation, further enhances the decomposition of peat, and CO 2 and N 2 O emissions. Cultivated organic soils are therefore significant sources of CO 2 and N 2 O. 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 CO 2 and N 2 O emissions from abandoned organic cropland soils do not generally decrease with time after agricultural practices have ceased, whereas CH 4 fluxes from the atmosphere into the soil may gradually increase after leaving cultivation.