Mitigation in Irrigated Rice Systems Project
Mitigation in Irrigated Rice Systems in Asia (MIRSA) project
The MIRSA project focuses on greenhouse gas mitigation in irrigated rice paddies in South-East Asia. Simultaneous experimental field trials were initiated in Sept 2013 in Jakenan (Indonesia), Nueva Ecija (Philippines), Prachin Buri (Thailand), and Hue (Vietnam), and continued for 6 seasons (3 years) to assess the site-specific feasibility of alternate wetting and drying (AWD) as a mitigation option for CH4 and N2O emissions from irrigated rice fields. The study aimed to develop standardised protocols on the effective implementation of alternate wetting and drying at multiple locations in South-East Asia to achieve the emission reduction target of 30% relative to the conventional water management, and to acquire a generalised scientific knowledge about the influence of alternate wetting and drying on GHG emissions reduction. The results have shown the effectiveness of alternate wetting and drying to reduce CH4 and N2O emissions.
The MIRSA project tests three different types of practice:
- Continuous flooding (used as the reference practice)
- Safe alternate wetting and drying: naturally drained until the surface water table reaches -15cm, then irrigated
- Site-specific alternate wetting and drying: based on scientific experience of each monitoring site (ie, this can differ in the practice among sites)
Each site was comparing safe AWD (drainage to 15cm below soil surface) and a site specific practice, alongside a continuously flooded field; although it
was noted that AWD was not able to be practice the sites from Thailand and the Philippines as high rainfall meant that the sites were never able to drain.
The average methane emissions from all sites (based on the site specific option) were found to be slightly higher than the default emissions factor provided by the IPCC, although not significantly higher. The sites that were able to practice AWD found that they were able to reduce water use and maintain the same yield as well as reduce methane emissions. A reduction in methane emissions was not always seen at the site where heavy rainfall prevented soils drying during a drainage event.