Date of Graduation

5-2025

Document Type

Thesis

Degree Name

Master of Science in Biological Engineering (MSBE)

Degree Level

Graduate

Department

Biological and Agricultural Engineering

Advisor/Mentor

Runkle, Benjamin R.

Committee Member

Moreno-Garcia, Beatriz

Second Committee Member

Reba, Michele L.

Third Committee Member

Koparan, Cengiz

Keywords

rice-fish co-cultivation; methane emissions; greenhouse gases; sustainable agriculture; eddy covariance method; fallow season management

Abstract

Co-cultivation of aquatic animals and rice in the same field is a fairly common practice in various parts of the world, with a number of well-established agro-ecological benefits, such as decreasing the need for chemical pesticides and fertilizers, increasing soil organic matter, and reducing the land area needed for agricultural production. One area of environmental concern in rice production is greenhouse gas emissions. Rice production contributes about 10% of global anthropogenic methane (CH4) emissions. Currently around 27.5% of Arkansas rice fields are flooded in the winter, which can increase CH4 emissions in the fallow season by 45% compared to non-flooded fields. Evidence from other systems suggests that co-cultivation techniques may reduce CH4 emissions through trophic cascading and provide a second revenue stream to farmers along with the rice crop. The objective of this research was to analyze the effects of cultivating golden shiners, a native fish species, on fallow season CH4 emissions in an Arkansas rice field using the eddy covariance (EC) method. This study uses a pair of long-term continuous rice rotation fields in Lonoke County, Arkansas to quantify the effects of golden shiners on fallow season CH4 emissions with fish added to one field and the other field left flooded without fish. Fluxes in both fields were found to be very low when compared to growing season emissions. Initial results on CH4 emissions reductions are mixed, and certain difficulties such as gaps in the data, lack of field replicates, and variability in soil properties and management practices between the fields make it challenging to derive robust conclusions about the impacts of fish presence on CH4 emissions. Incorporating water sample results, collecting more years of data, increasing the number of field replicates, and trying more alternative approaches like chamber measurements of CH4 flux could provide more insight into the ecological mechanisms at work in this system.

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