SUSTAINABLE WATER MANAGEMENT ACROSS THE AGRICULTURAL LIFE CYCLE AND REUSE OF OILFIELD PRODUCED WATER FOR IRRIGATION

Abstract

Water scarcity presents an ever-growing challenge in global agriculture, with significant implications for food security. In the United States (US), the scale and complexity of the agricultural system magnify these challenges, calling for an integrated and adaptive approach to water management. Among emerging solutions, the reuse of produced water (PW), a byproduct of oil and gas extraction traditionally managed using percolation pits and subsurface disposal, is being explored as a potential alternative water source for agriculture. However, its safe and sustainable application requires a comprehensive understanding of its impact across agroecosystem. This dissertation addresses these challenges through a multi-scale investigation of agricultural water sustainability, combining system-level analysis with controlled and field-based experiments. First, a review of six key strategies aimed at sustainable agricultural water management, including crop distribution optimization, soil management, modern irrigation technologies, water treatment and reuse, reduction of water demand in animal agriculture, and minimizing food loss and waste, provides a multidimensional perspective on optimizing water use in agriculture. In examining these strategies, several challenges emerged, including gaps in the current structure of incentives, psychological barriers, lack of awareness, reluctance to alter existing farming practices and consumption habits, and insufficient data on the effectiveness of certain water conservation measures. Building on this broader context, a greenhouse study examined the effects of irrigation with conventional produced water (CPW) on crop production, soil health, microbial diversity and function, and plant metabolome. Results showed that wheat grain metabolite concentrations, above-ground biomass, and plant height showed no significant differences across treatments, while grain yield was highest in the PW treatment. However, PW irrigation increased soil salinity and pH while reducing aggregate stability, suggesting potential long-term implications on soil health. Additionally, microbial communities in CPW-irrigated soil demonstrated functional shifts, including greater numbers of hydrocarbon degradation genes, indicating subtle ecological changes that may not be immediately evident through crop performance alone. To extend these findings to field conditions, a field study conducted in Orla, Texas evaluated the effects of treated produced water (TPW) irrigation on crop growth, soil chemistry, and the soil microbiome. Sorghum-sudangrass was grown under drinking water (DW) and TPW irrigation regimes. Post-harvest measurements showed no significant differences in aboveground biomass, and plant height was largely comparable across treatments. However, soil analysis revealed significantly elevated boron concentrations in TPW-irrigated soil and indicated limited microbial shifts in bacterial and fungal community composition. These results provide an important foundation for evaluating the viability of TPW irrigation and can support development of regulatory frameworks for TPW discharge in the Permian Basin. Lastly, a seed germination test was developed to evaluate a remediation strategy of PW-contaminated soils. PW spills can impair soil quality, and while Prussian yellow (PY) is proposed to be used as a remediation agent, its effects on seed germination are not well understood. Seed germination tests were conducted using native grass species, and results indicated that PY did not inhibit seed germination, and its addition to PW-contaminated soil did not increase cyanide toxicity in soil. Overall, this dissertation integrates experimental evidence to advance understanding of PW reuse in agriculture. By linking broader agricultural water management strategies with greenhouse and field-scale evaluations, this work contributes to the development of scientifically informed approaches for sustainable water management in agriculture.