Abstract
Digested liquid from methane fermentation (digested liquid) was applied to a bare field to clarify changes in the emissions of green-house gases from agricultural field soil to the atmosphere after application of digested liquid. It was found that the efflux of nitrous oxide from the soil increased and reached a peak 20 days after application of the digested liquid. In addition, that of carbon dioxide from the soil kept to be larger than that from soil without application of the digested liquid for more than 50 days. Estimation of the changes in the total amount of gases generated after application of the digested liquid showed that 0.17% of the nitrogen contained in the digested liquid was emitted as nitrous oxide and 22% of the carbon was emitted as carbon dioxide after 52 days. And the total amount of methane emitted after the application is negligibly small. Comparison of the total amount of gas efflux from the soil surface and gas diffusion through the surface soil demonstrated that 1/3 of the emitted nitrous oxide was generated in the surface soil and most of the emitted carbon dioxide came from the deeper soil layer. It is proposed that soil properties of surface soil affect the emission of nitrous oxide after application of the digested liquid, whereas that of the deeper layer is more effective to the emission of carbon dioxide.
