2023 Volume 79 Issue 25 Article ID: 23-25027
Production of animal feeds using composted sewage sludge (CSS), which can be domestically supplied, is expected to make a great contribution to food security in Japan where almost all of fertilizers and animal feeds need to be imported. This study investigated the emission of greenhouse gases (CH4 and N2O) from dent corn fields applied with CSS, comparing with fields applied with chemical fertilizers (CF) and pig manure (PM) as another organic fertilizer. As the results, quite low amount of CH4 was emitted from the fields regardless of used fertilizer. N2O was emitted at the beginning of the cultivation, especially from the field applied with CF. The emissions of these gases were converted to that of CO2 and integrated to calculate the total greenhouse gas emission (TGHG). Although there were no significant differences, using CSS and PM instead of CF could reduce the TGHG from dent corn fields by 33 to 55 %. We also found that dent corn production with application of these organic fertilizers can reduce a larger amount of greenhouse gases emitted in the production of chemical fertilizers than those from the fields. However, the comparable amount of greenhouse gases was emitted in the process of composting sewage sludge, highlighting the importance of controlling the composting process to achieve sustainable production of animal feeds with carbon neutral. In comparison, the emission of greenhouse gases in the transportation of chemical fertilizers produced in foreign countries to Japan was negligible.
