Life cycle greenhouse gas emission reduction potential of alternate wetting and drying in rice cultivation under Malaysian major granary areas

Abstract

Alternate wetting and drying (AWD) practices have been introduced in many countries as an approach to reduce rice GHG emissions. A detailed model of the AWD irrigation approach was compared to conventional irrigation systems in two main granary areas in Malaysia. The life cycle inventory of rice highlighted the areas where the cultivation stage would have the largest impact on raw materials and emissions. In the Penang and Selangor areas, soil GHG emissions accounted for 50 % and 80 % of the total rice life cycle greenhouse gas (LCGHG), respectively. Transitioning from conventional practices to AWD resulted in a reduction of these contributions to 46 % in the Penang area and 67 % in the Selangor area. The lower proportion of soil emissions in Penang is likely due to reduced capture of soil-based GHGs, influenced by varying environmental factors and soil conditions that affect the balance and type of GHGs emitted during cultivation. Additionally, different management practices in Selangor and Penang areas have been shown to contribute to different LCGHG emissions and rice yields. Notably, Selangor exhibits the highest LCGHG emissions and yields for conventional practices. However, the implementation of AWD in this area leads to the most significant reduction in emissions while maintaining high yields. Overall, these results highlight the importance of developing site-specific mitigation strategies that are adapted to local conditions. The implementation of AWD at a larger scale could contribute to Malaysia's climate commitments by lowering the carbon footprint of rice production.