Rice – a staple food for 3 billion people – consumes more water than any other crop, leading to unsustainable water withdrawals. Alternate wetting and drying (AWD) has thus been advocated instead of continuous flooding. However, AWD does not guarantee high yields and promotes decomposition of soil organic carbon (SOC) and loss of nutrients, reducing fertility. Moreover, the lack of flooding impairs the multi-functionality of rice systems. With this project, we will address this trade-off between water savings, rice productivity and provision of ecosystem services (ES). By budgeting the water cost of SOC protection, and by considering the advantages of water-related multi-functionality, we will approach the issue of rice sustainability in a more holistic way. We test the hypothesis that water savings from AWD are offset by reduced soil fertility and ES provision in three focus countries that span a range of growing conditions: Tanzania, Vietnam, and Italy. Soil analyses at our sites and global meta-analyses in combination to process models will provide the first estimate of the value of ES in rice systems, raise awareness of the intimate connections between rice and its soil, and suggest more sustainable practices and climate change adaptation measures.

Rice paddies in Piemonte (Italy), photo by S. Manzoni