Shrimp-rice model: Is it a sustainable development solution?

Although there are ecological conflicts between shrimp and rice, for now, in conditions where the irrigation system is not yet fully developed, the shrimp–rice model is a temporary solution that can bring benefits to farmers.

Some farming practices, if improved—such as selecting suitable varieties, optimizing water-management systems, and providing technical training—will help this model achieve higher efficiency. However, for sustainable development, it will be necessary to plan and develop specialized farming zones for shrimp and rice.

The shrimp–rice farming model is a combined production system in which shrimp culture and rice cultivation occur on the same area of land within a year. This model is applied in coastal regions (where irrigation systems are absent or incomplete), especially in the Mekong Delta provinces. It is a farming system that uses saline water during the dry season to culture shrimp and fresh water during the rainy season to grow rice, or shrimp and rice may coexist in the same area and period.

The shrimp–rice model includes two types of farming systems:

     - One shrimp crop/one rice crop (rotation): During the dry season, when salinity intrudes, shrimp are cultured. During the rainy season, when salinity decreases, rice is grown. Rice utilizes the sediment and organic sludge from the shrimp pond bottom for growth, helping clean the pond bottom for the next shrimp crop. However, because the substrate is soft mud and the water level is shallow, shrimp can only be cultured under extensive or improved extensive systems.

     - Rice cultivation combined with shrimp culture (intercropping): Rice fields are modified with perimeter canals or trenches inserted within the field to increase depth for shrimp stocking. In practice, shrimp and rice remain separated (shrimp in the trenches, rice on the field surface). Although water surface during early rice stages can be partially utilized, the effectiveness is low because mature rice shades the water and reduces benthic organisms that serve as natural feed for shrimp.

Benefits of the shrimp–rice model include:

     - Increasing household income through crop rotation or intercropping between shrimp and rice, allowing harvest of both commodities and maximizing land potential under limited irrigation. Reports indicate shrimp yields of 200–500 kg/ha/crop and rice yields of 3–6 tons/ha/crop.

     - Rotating shrimp culture and rice cultivation improves soil quality, reduces pond-bottom pollution (using shrimp waste as fertilizer for rice), and may reduce water pollution, limit disease outbreaks, and make use of natural seasonal cycles (rainy and dry seasons).

Constraints:

     - Scientific basis: Shrimp and rice require different ecological conditions. Rice grows in freshwater with soft, organic-rich mud and shallow water, while shrimp require saline–brackish water, firm and clean bottoms, deeper water levels, and high dissolved oxygen. Therefore, when intercropped, both shrimp and rice must survive under abnormal ecological conditions.

     - Rotational farming depends on natural seasonal patterns of saline (dry season) and freshwater (rainy season). If climate changes unpredictably—prolonged rain or drought—the transition between shrimp and rice cycles becomes difficult.

     - Poor environmental management can cause accumulation of pathogens and harmful microorganisms that affect both rice and shrimp. Shrimp are particularly susceptible to disease if water ecology becomes unstable or unsuitable.

     - The shrimp–rice model requires farmers to possess strong agricultural and aquaculture technical knowledge, including water-quality management, soil improvement, hydrometeorology, and crop/stock management. Without adequate training, farmers face challenges in production.

     - To operate an effective shrimp–rice system, farmers must invest in canals, pond systems, and water-management equipment within their land, creating financial pressure for households with limited capital.

     - Excessive use of fertilizers, pesticides, or antibiotics in the shrimp–rice model can pollute soil and water, degrade long-term field quality, and negatively impact future crops.

Origin and discussion

     - According to Resolution No. 09/2000/NQ-CP of the Government on policies for restructuring the agricultural economy and agricultural product consumption (June 15, 2000): “Inefficient rice-growing land should be converted to more profitable production, such as dry land into vegetable crops, and low-lying or coastal land into aquaculture.” This led to large areas of low-productivity agricultural and salt-production land in coastal provinces being converted to aquaculture. Due to insufficient planning and irrigation capacity, farmers used brackish or saline water for aquaculture, creating “overlapping zones,” from which the shrimp–rice model emerged.

     - Currently, the shrimp–rice farming area in the Mekong Delta is about 200,000 ha, producing nearly 120,000 tons annually. Provinces that strongly develop this model include Kien Giang, Ca Mau, Bac Lieu, and Soc Trang. According to reports, the Ministry of Agriculture and Rural Development aims to expand the shrimp–rice area in the Mekong Delta to 250,000 ha by 2030.

     - Statistics show that profits from the shrimp–rice model are 5–8 times higher than monoculture rice. However, when comparing monoculture rice, shrimp–rice, and monoculture shrimp, the shrimp-only model yields far greater economic efficiency, better land utilization, and improved environmental control.

     - According to Resolution 09/2000/NQ-CP, only low-efficiency rice land should be converted to more profitable production such as aquaculture. However, converting highly productive agricultural land into aquaculture can cause salinization, making soil difficult to rehabilitate for future agriculture, which may impact food security.

Overall, the shrimp–rice model is only a temporary solution (while irrigation infrastructure remains incomplete) and supports shrimp farming only under extensive or improved extensive systems. For sustainable development, significant investment in upgrading and completing irrigation systems is essential to establish clearly defined shrimp-farming zones and rice-farming zones.

From biological, ecological, economic, environmental, and production-management perspectives, specialized shrimp farming and specialized rice cultivation are the sustainable development pathways. This approach not only maximizes productivity for each sector but also minimizes ecological conflicts inherent in the shrimp–rice–shrimp cycle.

Translation from VIBO news. Author of Vietnamese article: according to (contom.vn – author Anh Vu)