Rice or Shrimp? Exploring current and future agro-ecological systems in Sóc Trăng province, Mekong River delta, Vietnam

Emilie Cremin (University of Glasgow), Irene Mussio (Newcastle University), Hue Thi Van Le (VNU-CRES), Siobhan Warrington (Newcastle University), Ly Bui Ha (CRES), Anh Nguyen (CRES). Acitivity organised by Hieu Hong Hua, Le Hoang Hai Anh, and Pham Kim Oanh (Can Tho University).

In September 2022, a group from the Living Deltas Hub team met with officers from the Department of Agriculture of Sóc Trăng province, in the Mekong Delta. This meeting was part of our field trip during the Hub’s Annual Meeting, which was coordinated by Can Tho University. Part of the objectives of this day trip was to better understand the changes in cultivation practices that have been taking place in the Mekong delta provinces, which has been mainly dominated by different types of shrimp farming and rice cultivation.  

Visit to the agricultural department of Sóc Trăng, (L-R) Susan Chilton, Irene Mussio, Hue Thi Van Le, Sylvie Nguyen, Ly BuI Ha, Anh Nguyen (Credit: fieldtrip member)

Sóc Trăng Land Usage

The Province of Sóc Trăng is mainly covered by agricultural areas: 32,573 ha of the 37.095 ha total area are cultivated. From inland to the coast, the province is dominated by rice cultivation, rice, and shrimp mixed farms, and mainly shrimp ponds or agro-ecological systems. 8173 ha are mainly cultivated with rice only, with two crops a year. There are 10 rice varieties cultivated from which 6 to 7 are high-yielding hybrid rice varieties. For example, varieties ST 24 (Sóc Trăng 24) and ST 25 (Sóc Trăng 25) rank among the varieties with the highest productivity at a global level. Farmers can usually produce more than 6 tonnes of high-quality rice per ha.  

Farmers are still very much attached to traditional rice cultivation. However, in the past 20 years the soil has become more saline. Therefore, the cultivation in the province has progressively shifted from rice to mixed shrimp-rice production. Shrimp-rice (one shrimp harvest + one rice harvest) currently covers 17,700 ha. In the same plot of land, there is a crop of shrimp in dry season, and rice, and vegetables in rainy season. Along the coast, the cultivation is dominated by shrimp as the soil is more saline on average, but some vegetables such as onions can be cultivated when irrigated with underground freshwater.

Changes to agro-eco-logical systems 

The intensive shrimp farming of the coastal areas needs oxygenation to avoid eutrophication. (Credit: Emilie Cremin)

The changes in agro-ecological systems are happening due to the decline of freshwater. The rate of water salinity has increased along the coast and inland, and water quality has declined since 2015. Farmers are facing challenges due to water pollution in the canals. Some canals are used to bring fresh water, whilst others are used to drain the wastewater contaminated by chemical waste from crop inputs or urban and industrial wastewaters. However, it is very common that farmers must use the polluted water for shrimp farming due to the lack of brackish water during the dry season.  

The sluice gates help to manage saline intrusion in Sóc Trăng. (Credit: Irene Mussio)

The changes in the agro-ecological system are also the result of individual and collective choices (both farmers and communities). The Vinh Chau District Administration gives advice to farmers on the rice and shrimp varieties depending on yield, quality, and price, but ultimate decision-making is left to the local communities. For example, Resolution 120 for the sustainability in the delta recommends that farmers are allowed to choose what they believe are the best crops for their land. This policy gives more freedom to farmers, who can choose to make modifications, such as removing embankments, when dikes are no longer helpful (however, embankments are still useful to separate sweet and salt water, and rice and shrimp farming zones). To control the water salinity, embankments (dikes) still serve as a limit between the brackish water and the brackish and saline water.

Visit to the agricultural department of Sóc Trăng, with Sylvie Nguyen, Irene Mussio, Virginia Panizzo, Andy Henderson, Susan Chilton, Hue Thi Van Hue Le, Siobhan Warrington, Emilie Cremin, Ly Bui Ha, Anh Nguyen (Credit: Hub member)

The sluice gates help manage saline intrusion in Sóc Trăng. (Credit: Emilie Cremin)

Cultivation choices  

Cultivation choices are also motivated by the income made from each crop. For example,  1.5 ha of rice will only generate 665 US$ income for wet rice or 415 US$ income for dry rice per crop. When two crops are cultivated income of 1,186 US$ (VND 30 million) per 1.5 hectare will be generated. While at the same time, for 1.5 ha of shrimp someone could earn 1,820 US$ per crop. The most profitable income per hectare is mixed shrimp and rice cultivation, which could give farmers up to 2,838 US$ (VND 70 million per year)2 gross returns (FAO, 2017). This model is currently promising as shrimp farming alone is facing different disease-related issues, which could lead to the failure of a season’s shrimp farming output.  

Our thoughts 

In conclusion, we can say that based on the information provided by the District Department of Agriculture and Rural Development of Sóc Trăng, the rice-shrimp farming remains the best option to maintain suitable water quality as water shifts and seasonal flows help clean the water and the soil in ponds. Even if there is a higher income from shrimp than rice, the farmers want to keep the rice-shrimp system as it is sustainable. However, we must keep in mind that some farmers are seriously affected by saline intrusion, which hampers their capacity to grow wet rice. Therefore, they could only farm shrimp (aquaculture) as their main source of income or diversify their sources of income with other seafood production such as crabs. 

References and further reads

FAO, 2017 : Grassi, F., R.T.Paris, Truong Thi Ngoc Chi. 2017. Rice–rice and rice–shrimp production : A gender perspective on labour, time use and access to technologies and services in southern Viet Nam. FAO. https://www.fao.org/3/i7277e/i7277e.pdf  

Kruse, J., Koch, M., Khoi, C.M., Braun, G., Sebesvari, Z., Amelung, W., 2020. Land use change from permanent rice to alternating rice-shrimp or permanent shrimp in the coastal Mekong Delta, Vietnam: Changes in the nutrient status and binding forms. Science of The Total Environment 703. https://doi.org/10.1016/j.scitotenv.2019.134758  

Nguyen, M., F. Renaud, Z. Sebesvari, and D. Nguyen. 2019. Resilience of agricultural systems facing increased salinity intrusion in deltaic coastal areas of Vietnam. Ecology and Society 24(4):19. https://doi.org/10.5751/ES-11186-240419  

Van Kien, N., Hoang Han, N., Cramb, R. 2020. Trends in Rice-Based Farming Systems in the Mekong Delta. In: Cramb, R. (eds) White Gold: The Commercialisation of Rice Farming in the Lower Mekong Basin. Palgrave Macmillan, Singapore. https://doi.org/10.1007/978-981-15-0998-8_17