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Climate change and water scarcity threaten the sustainability of rice production systems. Alternate wetting and drying (AWD) is a promising option to reduce methane (CH4) emission from irrigated paddy fields. However, its effect on rice yield remains to be clarified. Organic amendment can increase rice yield but may also increase CH4 emission. We therefore hypothesized that the combination of AWD with organic amendment could both increase rice yield and decrease CH4 emission. We carried out field experiments in six consecutive rice seasons during 2019 − 2022 in Central Java, Indonesia. We examined the effect of water management (continuous flooding [CF] and AWD) with (+M) and without (−M) the amendment of cattle manure as a locally available organic matter on rice growth and yield and the emissions of CH4 and nitrous oxide (N2O). AWD significantly (p < 0.05) decreased CH4 emission by 29% but marginally (p < 0.1) increased N2O emission by 10% relative to CF. There was no significant effect of AWD alone on rice yield. AWD significantly increased water productivity (the ratio of rice yield to irrigated water volume) by 50%. Cattle manure amendment significantly increased CH4 emission by 12% and rice yield by 5% but did not affect N2O emission. The combination effect of AWD+M relative to CF−M (control) was additive and resulted in a 7% increase in rice yield, a 19% decrease in the global warming potential (GWP) of CH4 + N2O emissions during both growing and fallow periods, and a 24% decrease in yield-scaled GWP. Our results indicated that the combination of AWD with cattle manure amendment would be a promising means to increase rice yield while reducing total soil greenhouse gas emission from irrigated rice paddies. [ABSTRACT FROM AUTHOR]

Water regimes play a central role in regulating methane (CH4) and nitrous oxide (N2O) emissions from irrigated rice field. Alternate wetting and drying (AWD) is a possible option, but there is limited information on its feasibility under local environmental conditions, especially for tropical region. We therefore carried out a 3-year experiment in a paddy field in Central Java, Indonesia to investigate the feasibility of AWD in terms of rice productivity, greenhouse gas (GHG) emission, and water use both in wet and dry seasons (WS and DS). The treatments of water management were (1) continuous flooding (CF), (2) flooding every when surface water level naturally declines to 15 cm below the soil surface (AWD), and (3) site-specific AWD with different criteria of soil drying (AWDS) established to find out the optimum for GHG emission reduction. Gas flux measurement was conducted by a static closed chamber method. Rice growth was generally normal and the grain yield did not significantly differ among the three treatments both in WS and DS. AWD and AWDS significantly reduced the total water use (irrigation + rainfall) as compared to CF. As expected, the seasonal total CH4emission was significantly reduced by AWD and AWDS. On average, the CH4emissions under AWD and AWDS were 35 and 38%, respectively, smaller than those under CF. It should be noted that AWD and AWDS were effective even in WS due partly to the field location on inland, upland area that facilitates the drainage. The seasonal total N2O emission did not significantly differ among the treatments. The results indicate that AWD is a promising option to reduce GHG emission, as well as water use without sacrificing rice productivity in this field. [ABSTRACT FROM PUBLISHER]

The increasing human population requires greater rice production. However, rice cultivation contributes to global warming through greenhouse gas (GHG) emissions. Technologies for reducing GHG emissions in concert with the increased rice production from rice fields are needed. The objectives of this study were to evaluate the effects of steel slag applications on methane (CH4) and nitrous oxide (N2O) emissions and rice yields. Two study sites were established at the experimental farm belonging to Indonesian Agricultural Environment Research Institute (IAERI) in Jakenan and a farmer’s field in Wedarijaksa sub-district, Indonesia. Both field trials were conducted during the dry season (DS) of 2009 and the rainy season (RS) of 2009/2010. During the DS, a randomized block design was arranged with two treatments (a control and a steel slag application at 1 Mg ha−1), which were replicated five times. During the RS, the experimental plot with 1 Mg ha−1of steel slag treatment was split into two small sub-plots to accommodate the additional 1 and 2 Mg ha−1steel slag treatments. The results showed that there was a decreasing tendency in the CH4emissions at both sites and during both seasons after steel slag applications, although there was no statistical significance. During the RS in Jakenan, steel slag applications at rates of 1 and 2 Mg ha−1decreased the CH4emissions by 9.1 and 10.7%, respectively. In Wedarijaksa, steel slag applications at rates of 1 and 2 Mg ha−1decreased the CH4emissions by 12.6 to 18.7%, respectively. The N2O emissions were decreased by 34 and 38% following slag applications at the 2 Mg ha−1rate during the RS in Jakenan and Wedarijaksa, respectively. The iron content of steel slag could be used to reduce not only CH4but also N2O emissions. Increased level of electron acceptors suppresses CH4and N2O emissions. The application of steel slag at 1 and 2 Mg ha−1increased rice grain yields by approximately 4.8–5.6% in Jakenan and 0.3–4.7% in Wedarijaksa. It might be better to apply steel slag at higher rates for more than two growing seasons to reach reduction in CH4and N2O emissions. [ABSTRACT FROM AUTHOR]