Water scarcity, declining soil fertility and crop-residue burning are increasingly affecting agricultural production across the Greater Mekong Subregion (GMS), with climate change intensifying droughts, floods, salinity intrusion and rainfall variability. Prepared under the Asian Development Bank’s Greater Mekong Subregion Sustainable Agriculture and Food Security Program, this policy brief examines challenges and investment priorities for Cambodia, Lao PDR, Thailand and Viet Nam. Smallholders are particularly exposed because of gaps in irrigation, advisory services, climate information, finance and access to climate-resilient practices.

The brief identifies uneven adoption of climate-smart agriculture (CSA) and nature-based solutions (NbS) as a systemic challenge rather than simply a shortage of appropriate practices. Fragmented governance, limited soil and water data, weak monitoring, reporting and verification (MRV) systems and thin last-mile service markets constrain implementation. Gender barriers can further restrict women’s access to digital services, finance and decision-making. Proposed responses include integrating digital advisory services and early warning systems into extension, establishing interoperable soil–water data and MRV standards, expanding risk-sharing and results-based finance, and developing service-provider markets for soil diagnostics, irrigation and crop-residue management.

For 2026–2030, the brief recommends adapting these measures to national circumstances. Priorities range from strengthening basic diagnostics and advisory services in Cambodia and Lao PDR to expanding interoperable MRV, traceability and performance-based financing in Thailand and Viet Nam. Regional coordination is emphasized to improve water-use efficiency, soil health and climate resilience.