Date of Graduation

12-2023

Document Type

Thesis

Degree Name

Bachelor of Science in Biological Engineering

Degree Level

Undergraduate

Department

Biological and Agricultural Engineering

Advisor/Mentor

Runkle, Benjamin

Committee Member/Reader

Liang, Lu

Committee Member/Second Reader

Henry, Christopher

Abstract

Rice grown in 5 states across the Mid-South (AR, LA, MS, TX, and MO) account for nearly 80% of all domestic U.S. rice production. Methane emissions produced during rice farming and the large seasonal water demand to maintain flooded fields have created a need for alternative irrigation research that can reduce methane emissions and conserve water. Structures called eddy covariance towers (ECTs) can observe methane and other flux responses to changing irrigation styles, and their data is shared across flux tower networks such as Delta-Flux in the Mid-South. The Delta-Flux network is relatively new, and its data-sharing capacity is not fully developed. This research seeks to analyze the extrapolation potential for data collected by ECTs to be used across rice growing regions in the Mid-South as well as identify areas for future tower placements that will increase the spatial variance represented by the network.

Twenty variables that characterize the bioclimatic, landscape productivity, and soil composition features of the study area were analyzed to construct an overall ecological profile for all rice regions in the Mid-South. Numerical scores were assigned to each variable based on its importance to rice growth characteristics. Data for each variable was extracted from a 2000m radius of the 22 ECT sites and plotted across the study area using the scores to identify rice regions with highly similar environmental features as the ECT locations. The same process was used to analyze data outside the represented ranges and identify ecologically underrepresented regions in the Mid-South. Adjustments to the initial variable scores were assigned to the underrepresented ranges based on two parameters including presence of local maxima and total percent of data not represented by ECTs.

The overall ecological profile of the rice regions shows that the ECTs in rice fields throughout the Delta-Flux network represent mainly warm, dry locations with higher percent clay values. The most underrepresented rice regions are located along the southern Louisiana and Texas coasts and are characterized by warmer temperatures, low temperature variability, small annual temperature ranges, and greater precipitation. By analyzing environmental trends throughout the Mid-South, future ECTs can be placed in more underrepresented areas that expand the network ecological profile. Ultimately, by increasing the extrapolation potential of the Delta-Flux network, data from ECT experiments can support broader efforts to develop newer, more efficient irrigation systems for rice fields.

Keywords

eddy covariance tower; methane emissions; representativeness evaluations; rice; Delta-Flux

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