The effect of fertilizer and manure application on CH4and N2O emissions from managed grasslands in Japan

The objectives of this study were to clarify the effect of chemical fertilizer and manure application on methane (CH4) and nitrous oxide (N2O) emissions from intensively managed grassland on Andosols in Japan and to determine the controlling factors of the CH4 and N2O emissions. The emission factors (EF) for both fertilizer- and manure-induced N2O emissions were calculated. Three experimental plots were set up in five grasslands across four climatic regions in Japan: one plot for treatment with chemical fertilizer (fertilizer plot); another plot for treatment with cattle manure and chemical fertilizer (manure plot), and the final plot was not treated with chemical fertilizer or manure (control plot). The type of chemical fertilizer was ammonium-based fertilizer or a combination fertilizer of ammonium and urea. CH4 and N2O emissions were measured at the study sites for six years. For the manure plot, a supplement of chemical fertilizer was added to equalize the supply rate of mineral nitrogen (N) relative ...