Date of Award

5-2026

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Plant and Environmental Science

Committee Chair/Advisor

Dr. Dara Park

Committee Member

Dr. Brook Russell

Committee Member

Dr. Debabrata Sahoo

Committee Member

Dr. Qiong SU

Abstract

Over the years, the environment around us has been influenced and shaped by anthropogenic drivers, including deforestation and the large-scale use of fossil fuels. This has disrupted the carbon cycle, increasing atmospheric CO2 levels and driving climate change. Challenges associated with climate change, such as hotter temperatures, more intense rainfall events, and longer dry periods, are affecting soil moisture dynamics, degrading soil health, and threatening food security within cropping systems. To help protect soil health and improve soil functions, cover cropping has been promoted as a management practice in agroecosystems. While cover crops (CCs) provide many benefits, farmers are hesitant to adopt CCs due to uncertainties about how unpredictable weather may affect CC establishment and growth, and how CCs may influence plant-available water for the subsequent cash crop and thus impact crop yields. To provide insights into these uncertainties, this dissertation investigates CC performance and how CCs affect soil water dynamics and subsequent cash crop yields within agroecosystems in the Southern Piedmont Region of South Carolina. The works presented in this dissertation include a literature review exploring how climate change may affect food security and three field studies investigating different aspects of CCs and their short-term effects on soil health. The literature review highlights how conditions associated with climate change create an environment more conducive to the development of soil water repellency (SWR), which may further threaten food security. Because SWR is influenced by organic materials, management practices that increase organic matter, such as cover cropping, are also thought to influence SWR. Chapter three builds off this idea and investigates the water repellency of CCs and their residues. The results show that CCs are water-repellent, and the level of repellency varied among CC species. This information provides valuable insights that can help farmers identify appropriate CC species to plant when managing soils susceptible to SWR. The second field study examines how planting conditions and timing affect CC establishment, growth, and short-term changes in soil health parameters over two years. During the first year of the experiment, cereal rye and annual ryegrass were planted as monoculture CCs at two different times (early and late). During the second year, the same monoculture CCs were planted under two contrasting moisture conditions (ideal and dry). This study demonstrates that even under unpredictable weather conditions and planting delays, CC establishment can still be successful, producing adequate soil coverage that helps to suppress weeds and protect soil aggregates. The final field study evaluates how CCs influence soil moisture under subsequent cash crops and how CCs impact subsequent cash crop yields. The soil moisture data show that CCs can help conserve soil moisture within shallow depths (15 cm) throughout the soybean season by reducing evaporation losses. Cover crops did not influence soil moisture in the deeper horizons (45 cm). The data collected also reveals that CCs did not hurt soybean yield. Instead, soybeans following CCs produced higher yields than those following a fallow (bare) period. Collectively, this dissertation highlights opportunities and considerations for implementing CCs in cropping systems in the Southern Piedmont region of South Carolina.

Author ORCID Identifier

0009-0008-4025-6568

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