Date of Graduation

7-2020

Document Type

Thesis

Degree Name

Master of Science in Crop, Soil & Environmental Sciences (MS)

Degree Level

Graduate

Department

Crop, Soil & Environmental Sciences

Advisor/Mentor

Kristofor R. Brye

Committee Member

Christopher G. Henry

Second Committee Member

Lisa S. Wood

Third Committee Member

Edward E. Gbur

Keywords

correlation analysis, fluxes, furow-irrigated rice, Globak warming potential, greenhouse gases, multiple regression analysis

Abstract

Alternative water management practices for rice (Oryza sativa) production have been developed for water conservation purposes, such as the relatively new furrow-irrigated rice production system, which results in spatially variable volumetric water content (VWC), temperature, and oxidation-reduction (redox) potential. No research has been conducted to relate greenhouse gas (GHG) production to soil and plant properties or environmental factors under furrow-irrigated rice. The objective of this field study was to evaluate correlations between methane (CH4), nitrous oxide (N2O), and carbon dioxide (CO2) fluxes and emissions and global warming potential (GWP) and near-surface soil properties and environmental factors over two growing seasons (2018 and 2019) under furrow-irrigated rice on a silt-loam soil in eastern Arkansas. Gas samples were collected weekly between planting and harvest from enclosed-headspace, static chambers and analyzed by gas chromatography. Methane fluxes were correlated (P < 0.01) with VWC (r = 0.18) and soil redox potential (r = -0.59), N2O fluxes were correlated (P < 0.01) with soil redox potential (r = 0.13), and CO2 fluxes were correlated (P < 0.05) with VWC (r = 0.29), soil redox potential (r = -0.27) and soil temperature (r = 0.09). Methane and N2O emissions were positively (0.36 < r < 0.78) and negatively (-0.33 < r < -0.54) correlated (P < 0.01) with numerous soil and plant properties. Significant multiple regression models predicting season-long CH4-C, N2O-N, CO2-C, and GWP from a suite of soil and plant properties were identified (0.49 < R2 < 0.78). Results of this study demonstrated numerous soil, plant, and environmental factors substantially control GHG production and release, which can be used to mitigate GHG emissions from the furrow-irrigated rice production system to improve current and future sustainability of rice production in the United States.

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