Effect of soil tillage and nitrogen fertilizer management on methane emissions from irrigated rice fields in Central Java, Indonesia

Rice (Oryza sativa L.) production in the future aims to increase productivity every year with high input technology, including irrigated rice. However, the practices of irrigated rice fields have a high methane (CH4) production potential. Soil tillage could affect CH4 emission conditions. Puddling and flooding through soil tillage create reduction conditions that promote CH4 production by methanogenic bacteria. The objective was to determine the effect of soil tillage and N fertilizer management on CH4 emissions from rice fields with heavy-textured soil. The field experiment was arranged in a split-plot design in which soil tillage was the main plot and consisted of maximum tillage and no-tillage. Nitrogen fertilizer management was the split plot and consisted of a control without N, prilled urea broadcasting, prilled urea deep placement, ammonium sulfate (AS) broadcasting, AS deep placement, and tablet urea deep placement. No-tillage could reduce CH4 emissions by 15.58% compared with maximum tillage. However, grain yield for no-tillage was lower than for maximum tillage with 2.73 and 3.68 t ha-1, respectively. The AS and tablet urea deep placement emitted lower CH4 and grain yield was higher than with other N management practices. The CH4 emissions for AS and tablet urea deep placement was 96 and 97 kg CH4 ha-1 season-1 and grain yield was 3.79 and 4.25 t ha-1, respectively. The application of fertilizers incorporated into the soil increased rice productivity and mitigated CH4 emissions from rice fields.