Fish Before Irrigation: Maximizing Water Use for Fish and Crop Production
This post was written by Karen Veverica, External Advisory Board member for the Feed the Future Innovation Lab for Fish and retired director of the E.W. Shell Fisheries Center at Auburn University. The Center of Excellence on Sustainable Agricultural Intensification and Nutrition (CE SAIN) was an implementing partner of the Fish Innovation Lab’s Bighead Catfish Culture Activity and works closely with other Innovation Labs, including the Feed the Future Innovation Lab for Collaborative Research on Sustainable Intensification.
As water resources get tighter and irrigation solutions are seen as “modern, high technology” agriculture, aquaculturists have been trying to get irrigation system designers to consider designing a first use of the water for aquaculture before the water is used to irrigate crops. However, irrigation schemes rarely consider using water for anything but irrigation. Runoff post-irrigation has been used for aquaculture in Egypt for decades, but this water often contains unsafe levels of pesticides. Using the water for aquaculture before using it for irrigation allows us to benefit from a second use of the nutrients.
Fish Before Irrigation (FBI) is a type of aquaponics, but it is different in its outlook. FBI sees the plants as the main crop and the fish get added into the system in a way that least disturbs the production of the agricultural commodities.
For example, a small project conducted in Senegal identified well-functioning women’s cooperative gardens and funded the addition of fish tanks to function as additional water storage tanks. The size of the tanks depended on the total water being pumped for daily watering of vegetables. A daily water replacement rate of one-half the tank volume was used. In Senegal, the water delivery system depended on hand-watering of vegetables. Due to the nutrients in the fish tank water, plant yields and health improved, the women were able to make a small profit from the fish production and the supply of a high-value protein increased in the village.
Previous work funded by USAID showed that using water from pond aquaculture systems had positive impacts on the growth of French beans in Kenya.
CE SAIN, established through the Feed the Future Innovation Lab for Collaborative Research on Sustainable Intensification, in Cambodia seeks to do something similar: produce fish intensively in small tanks before moving the water to a solids settling tank and then sending the water to the crops by a drip irrigation system. Various drip emitters can later be tested for best results. It is hoped that the cost of fertilizing the vegetables can be reduced and that the fish production will either break even or result in some profits.
CE SAIN has been operating a Certification of Aquaculture Professionals course and a short, two-day FBI course is being introduced for teachers in secondary schools in late January 2024. Following the course, the teachers will be able to set up their own demonstrations at the school gardens, with some small financial assistance from CE SAIN. The participants will learn about irrigation, fish production, business planning and marketing. They will build a system themselves and learn to record growth and water quality results. Costs of production for the vegetables and for the fish will be tracked.
These systems are designed to produce multiple benefits. Removing the water from the bottom of the tanks captures the solid wastes, benefitting the fish. Applying the solids directly to the soil serves as a fertilizer for the plants. This also means the supernatant, or water at the top of the tank, has fewer solids and can then enter the drip system that first filters the water before sending it to the emitters.
An FBI approach can boost agricultural production, enhance dietary diversity and increase incomes through livelihood diversification. Leveraging the support of USAID and Feed the Future through collaborations with partners like CE SAIN holds great potential for sharing this approach widely and creating impact at scale.