Researchers are pioneering a system in Arkansas to turn winter-idle rice fields there into productive fish farms, potentially offering environmental benefits and a new revenue stream for growers.
Currently, rice is planted in the spring and harvested in the fall, leaving the fields empty in winter. But what if this non-productive period could be utilized to add a second, lucrative crop?
The ‘Fish In The Fields’ Project
University of Arkansas researcher Ben Runkle is exploring that question with his multiyear research project called, “Fish in the Fields.”
Runkle says the research is being conducted on a commercial rice farm in eastern Arkansas in Lonoke County, about 45 minutes east of Little Rock.
“The concept was introduced to us by partners from California, at the Resource Renewal Institute, who are interested in exploring different types of regenerative production that are environmentally-friendly and farmer-friendly,” Runkle says.
Scientists at the Institute reached out to Runkle and his group, knowing their expertise in agriculture and farm practices and the interactions between the carbon and water cycle.
“We started designing this experiment to explore the potential for growing fish as a crop, concurrent, or in the off season, with rice,” Runkle says.
The researchers are evaluating two key potential benefits:
- environmental/agronomic: The fish can help consume and degrade some of the leftover residues of the rice plant. They are also theorized to reduce methane emissions from the field in the winter period, Runkle notes. Additionally, they process and cycle nutrients, which could potentially reduce fertilizer needs for the subsequent rice crop.
- economic: The fish provide an alternate source of income for the farmers if they are harvested and sold on the market.
Runkle says there are a couple of similar projects he’s aware of that are underway in the U.S. One is in Louisiana, where rice farmers are doing some rotation with crawfish in their fields. There are also some similar projects underway in California, with researchers and farmers there exploring the use of fish in the wintertime to help break down residues.
Small Fish, Big Impact
Runkle says the Arkansas project is currently focused on growing fish commonly referred to as darters.
“They’re very small fish, basically like minnows. They are most commonly used as feed for other fish,” he explains.
The 2024 winter marked the third time Runkle and his research team have raised the fish in the field. In the process, they developed a prototype system to turn the fish into a marketable product.
“They are being flash freeze-dried, packaged, and will be sold as fish food,” Runkle says.
Along with developing a marketable product, Runkle says his team’s work has demonstrated some regenerative agriculture benefits.
“My graduate student’s research has found very low methane emissions in these fields, which is an environmental benefit,” Runkle says. “We also have some evidence of the fish consuming the leftover residue in the field, which provides an agronomic benefit.”
Along with those efforts, Runkle and hist team are taking water samples to assess zooplankton and phytoplankton, and flying a drone over the field to measure chlorophyll content. “It’s a highly integrated, real-world measurement system,” he says.
De-Risking The System For Farmers
Future phases of the research will continue to look at how farmers could benefit financially from including fish as a second crop in their fields during winter while incurring a low level of risk. Being able to produce an additional “crop” on fields could provide a financial boost to rice growers in Arkansas, the No. 1 rice-producing state in the country, and potentially, for rice growers in other states.
Runkle says his group is evaluating how to “de-risk the system” by making sure it demonstrates a clear profit, does not impact farmers’ main crop of rice and offers a reliable market for the uniquely grown fish.
“We would like to study more about the methane dynamics, the fish productivity, and critical harvest methods. A major factor is improving the harvest, which currently involves draining the fields just right to congregate the fish in a ditch, and then using a special pump system to collect them. It requires year-by-year iteration to improve,” Runkle notes.
Runkle says financial support by the Southern SARE Grant (Sustainable Agricultural Research and Education) and an NRCS Conservation Innovation Grant is funding the research.
To learn more about the fish-in-fields project, listen to the recent podcast, Short Talks From The Hill, where host Hardin Young and Runkle discuss the research and the potential opportunities for farmers.
