Salinity and Rice Production in Vietnam Mekong Delta

The decision

Sea-level rise is pushing saltwater further into the Mekong Delta, Vietnam’s main rice-growing region, and many coastal fields are becoming less suited to rice. Farmers can adapt rice production in place, with salt-tolerant varieties and salinity barriers, or move their land into other uses. Policy has tended to back one path or the other: large infrastructure that locks farmers into intensive rice, or support for finding alternative land uses. Choosing between them needs evidence on how much salinity actually costs rice farmers and what makes them stop growing rice.

Approach

The project surveyed rice-growing households in salinity-prone areas of the delta across several cropping years, building field-level panel data. The first paper uses a two-year panel of 788 households. Fixed-effects regressions estimate how salt-tolerant varieties affect yields, and probit and IV-probit models explain which fields leave rice production. The second paper uses three years of data from 758 households to estimate how salinity exposure affects field-level rice profits and how expected profits shape decisions to exit rice.

What this supports

• Salt-tolerant varieties raise yields on fields not protected by salinity barriers, but their lower market prices limit the overall economic gain.
• Farmers stopped growing rice on 15% of surveyed fields. Falling profitability drives these exits, while salinity barriers, large rice holdings, and community commitment to rice farming are associated with staying in rice.
• High salinity cuts average field profits by more than 75%. Exits rise once expected profits fall below about 20 million VND per hectare, and farmers form those expectations from both the latest season and past extreme salinity events.

The first paper concludes that support for adaptation should blend the two polarized policy options, investment in rice infrastructure and support for farmers moving to other land uses, rather than choose between them.

My role

As a research assistant and data analyst at the International Center for Tropical Agriculture (CIAT) from 2019 to 2022, I developed the questionnaires and CSPro survey programs, supervised data collection, managed and cleaned the survey data, and built econometric analysis pipelines in R and Stata that contributed to both papers.

Publications

• Mills, Bradford, Dung Phuong Le, Duong Phuc Ta, Lien Nhu, Danh Thanh Vo, and Ricardo Labarta. 2022. “Intensive and extensive rice farm adaptations in salinity-prone areas of the Mekong Delta.” Climate and Development 15(2): 162-176. doi:10.1080/17565529.2022.2072800
• Mills, Bradford, Chi Ta, Duong Phuc Ta, and Huong Nguyen. 2025. “Salinity Inundation, Profitability, and Rice Farming Exits in Mekong Delta of Vietnam.” Journal of the Agricultural and Applied Economics Association 4(2): 170-186. doi:10.1002/jaa2.70004 (open access)