Alternate wetting and drying reduces methane emission from a rice paddy in Central Java, Indonesia without yield loss

Abstract

Water regimes play a central role in regulating methane (CH 4 ) and nitrous oxide (N 2 O) 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 CH 4 emission was significantly reduced by AWD and AWDS. On average, the CH 4 emissions 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 N 2 O 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. ARTICLE HISTORY

Mitigation Potential and Yield-Scaled Global Warming Potential of Early-Season Drainage from a Rice Paddy in Tamil Nadu, India

“…As expected, alternate wetting and drying conditions were effectively maintained in the Full-AWD throughout the rice growing period of dry season; however, there was also sufficient soil drying that was achieved even under high rainfall conditions of the wet season (Figure 2), which resulted in reduced CH 4 emission from either crop season (Figure 5a,b). This result is in line with findings of other studies [2,11,15,17,32]. Reductions in the irrigation water in the Full-AWD treatment led to a lower surface standing water depth ( Figure 2) in both rice seasons, which increased oxygen penetration into the soil and led to soil organic carbon being oxidized to CO 2 instead of CH 4 , thus suppressing CH 4 emissions [33].…”

“…Previous meta-analysis results show that AWD irrigation conducted only during the vegetative or reproductive phase results in no yield reduction compared to an 8.1% yield reduction when it is practiced throughout the whole season [9]. Other studies have also reported no yield losses when implementing AWD irrigation compared with CF [11,32]. The results mean that there is no necessity to maintain continuous standing water throughout the rice growing season since irrigated rice had developed adaptability to the intermittently flooded conditions [49].…”

Site-specific feasibility of alternate wetting and drying as a greenhouse gas mitigation option in irrigated rice fields in Southeast Asia: a synthesis

“…That is, the plots were irrigated when the water level dropped to 5 cm, 10 cm, and 15 cm below the soil surface at early tillering stage, late tillering stage, and grain filling and ripening stage, respectively (Tran et al 2018). In Jakenan, multiple aeration 7 days before the 1st and 2nd N fertilizer topdressing was implemented as AWDS in the first two seasons, and in the succeeding seasons, the threshold of re-flooding changed to 25 cm below the soil surface (Setyanto et al 2018). In Prachin Buri, the plots were re-flooded to 10-cm level under AWDS as compared to 5-cm level under AWD (Chidthaisong et al 2018).…”

“…They represent diversified paddy environments in Southeast Asia. Results from each site were reported in separate papers of this issue (Tran et al 2018;Setyanto et al 2018;Chidthaisong et al 2018;Sibayan et al 2018). They monitored the changes in soil carbon (C) content, which may be lost by intensive drainage events, in addition to CH 4 and N 2 O emissions under AWD and CF.…”

Field Validation of the DNDC-Rice Model for Methane and Nitrous Oxide Emissions from Double-Cropping Paddy Rice under Different Irrigation Practices in Tamil Nadu, India

“…Water management is one of the most effective options for reducing CH 4 emission from irrigated rice. Recently, midseason drainage and alternate wetting and drying irrigation (AWD) practice have been promoted as a strategy to decrease CH 4 emissions from paddy rice fields [3,[5][6][7][8]. However, it can result in increased N 2 O emissions due to a trade-off between CH 4 and N 2 O [2,3,9].…”