Fish in the Fields: Increasing Sustainability of Existing Rice Farming Practices with Supplemental Aquaculture

View the project report

Commodities

• Agronomic: rice
• Animals: fish

Practices

• Animal Production: aquaculture
• Crop Production: methane reduction

One simple solution: Adding fish to rice fields.

Fish add an additional income stream to acreage used to grow rice in the summer, creating year-round productivity and a new revenue source from virtually the same amount of land and water. And, when young fish are introduced, initial research has indicated they have the potential to reduce methane emissions by up to two-thirds.

FIF’s original controlled study was conducted on California rice farm sites from 2012-2018. Collaborating with farmers, University of Montana aquatic ecologist, Dr. Shawn Devlin, scientists from UC Davis and the California Department of Fish and Wildlife (CDFW), controlled experiments were performed comparing paddies with fish to those without fish. In 2018, FIF demonstrated that ponds with fish emitted 65% less methane than ponds without fish. This striking methane reduction is the result of a trophic cascade, a process that occurs when fish alter the microscopic food chain of the nutrient-dense flooded rice fields.

Aligning with SARE’s grant program focus areas, 2 and 7, FIF creates affordable, effective incentives for farmers to adopt conservation and stewardship practices. FIF introduces fish into winter-flooded rice fields as a seasonal second food product, which serves as both a market-driven economic incentive and a multi-benefit conservation practice for working landscapes. To date, we have found:

• Initial data has found that rice fields are 10x more productive for raising fish than wild systems,
• Unlike commercial aquaculture practices, FIF requires no additional expensive fish feed. 
• The addition of small fish to fallow, flooded rice fields may significantly reduce methane emissions associated with winter
• Seasonally flooded landscapes support biodiversity, wetland habitat connectivity via migratory flyways and fish passages
• FIF integrates easily into existing rice systems where winter flooded fields enable bird habitat and waterfowl hunting, producing a second annual crop without additional land/water usage.

In October 2022, research on the FIF system was expanded to Arkansas – the largest rice producing state in the United States. The research is ideally sited at Isbell Farms, where Dr. Benjamin Runkle and his University of Arkansas Landscape Flux research group has spent the last eight years studying the connections between carbon and water cycles in agricultural and wetland environments (Moreno-García et al., 2021; Runkle et al., 2021, 2019, 2017; Karki et al., 2023, accepted and forthcoming). The FIF project benefits from the University of Arkansas group’s depth of knowledge and expertise, their existing infrastructure of research plots, as well as the use of their highly sophisticated GHG-measuring flux towers. In addition, the entire project is made possible through a generous in-kind donation from the Isbell family, who have provided 140 acres of land, water and farm equipment, supplies and expertise. 

Our long-term vision is that Agriculture must sustainably adapt to an era of climate change to continue to feed the world, and FIF can play a role in stimulating this transition. The global food system accelerates climate change, which in turn disrupts traditional weather patterns and affects global agriculture, politics and hunger. Since roughly one third of human-caused greenhouse gas emissions come from agriculture, Fish in the Fields can affect policy change from a systems approach based on science, natural resource management and public-private partnership. FIF’s methane reduction strategy harnesses ecological principles to ensure long-term productivity of rice-growers and the rice/wetland ecosystem year-round, which in turn supports increased water conservation, species diversity, and wildlife habitat. 

Funding in this SARE project will enable activities in three main areas: 

1. Synthesize research findings from the ongoing pilot project, which supports great measurements by latching onto ongoing measurement campaigns but lacks support to provide synthesis of findings. In particular, this project will allow a clearer contrast between adjacent fish-amended and control (no-fish) fields, based on comparison of a broader suite of agronomic, environmental, and production data. 
2. Education and outreach. The project team will develop and deliver educational materials for presentation in annual Field Day Events, hosted on-site in Arkansas to a wide audience of farmers (rice producers, fish farmers), extension and research scientists, and supply chain partners. 
3. Feedback on project aims. We anticipate that the Field Days will enable ample time for structured interactions and discussions with participants to assess how the FIF concept can be extended beyond the test farm. The participants will provide feedback on ways to improve the FIF concept, rigorously question stated outcomes, and be involved in the design of a new vision for integrated fish-rice production in Arkansas.

Fish in the Fields (FIF)  is seeking answers to the question of how fish can be used to reduce methane emissions from rice. All necessary conditions are present for the replication of prior research protocols and results in California. We believe that applying Dr. Devlin’s research to Arkansas’s rice fields via FIF will provide the scientific basis for expanding rice-fish farming systems across rice acreage worldwide, which will in turn, strengthen FIF’s work to its initial goals of sustainable agricultural innovation, water conservation, migratory waterfowl habitat preservation, and social enterprise. RRI’s years of preliminary work have allowed FIF to establish the parameters for experimentation ( e.g., fish species and size, plankton abundance and diversity, water quality and source, field design) and expand the scope of work to include carbon cycling in existing FIF rice-fish farming system. Understanding why and how fish can be used to reduce methane burden.

How Fish in the Fields works.
In the Spring, rice fields are flooded and prepared for the 120-day rice growing season. After rice is harvested in the fall, the straw residue is either burnt or incorporated and the fields are reflooded to decompose the remaining rice straw and provide waterfowl habitat. This is where Fish in the Fields comes in. We plant fish in winter flooded fields, where they grow rapidly on naturally abundant plankton until they are harvested in March, when the cycle repeats. FIF’s strikingly simple, replicable design is possible because of the favorable qualities of the minnow species–robust growth, tolerance of temperature fluctuation, prolific reproduction and a diet of zooplankton. No additional food, water or land are needed. 

During our research period, FIF’s convergence of test sites, farm partnerships, hatcheries and team of advisors provided a perfect opportunity to study and test how the addition of fish affects rice field productivity and methane emissions in California rice fields. The results were positive and encouraging. Rice fields proved to be ten times more productive in growing fish than wild systems, and the addition of fish reduced the methane emissions from rice production - dramatically - by as much as 65%. Our test ponds also served as a site for the development of many innovations in pond and hatchery design and harvest methods, as well as the discovery of relevant academic research, all of which refined and improved the FIF model (hereafter referred to as the “FIF Winter Protocol”).   

Arkansas FIF 3 year Pilot

The FIF Arkansas demonstration project (est. 2022) is a partnership involving Key Project Cooperators to assess feasibility of FIF practices in Arkansas. Launched in mid-October, 2022, FIF is a landscape-scale pilot project to research and quantify how the addition of fish to fallow flooded rice fields impacts fish growth, and how it affects the methane emissions associated with winter flooding of rice fields. 

Site, Scope and Capabilities:

The 3-year, 140-acre (one 70-acre test plot and one 70-acre control plot) study will be hosted by Zero Grade Farms, an Isbell Family Partnership in England, AR, in the heart of the Southeastern rice-growing region. A leader in innovative sustainable rice-growing practices, Isbell Farms is already the site of a multiyear University of Arkansas greenhouse gas study that will provide the FIF research team with existing infrastructure and sophisticated measurement tools. Among them are two eddy covariance towers that furnish greenhouse gas emissions data around the clock, including methane, nitrous dioxide, and carbon dioxide.

Primary Research Objectives :

• Measure the efflux of GHGs in fish-present and fish-absent winter-flooded in comparable and adjacent 70-acre field plots. 
• Produce data on dissolved oxygen, zooplankton abundance, bird predation and fish mortality associated with the preferred FIF stocking density (100 lbs/acre) of golden shiners.
• Quantify total production (lbs. in/lbs. out) of fish biomass for juvenile golden shiners in winter-flooded rice paddies in central Arkansas. 
• Conduct initial fish growth modelling for juvenile golden shiners in winter-flooded rice paddies in central Arkansas.
• Calculate the amount of methane present in flooded rice paddies that is converted into fish biomass via the process of “trophic shunting”.
• Conduct initial studies into how the introduction of fish helps rice fields cycle and retain nutrients.  
• Develop areas for further research. 

Project activities will follow in the collection of this set of research activities, synthesis and discussion among project participants, and the development of tractable educational materials for presentation and communication at the funded Field Days.