Tile Drainage in The U.S. Midwest: Interconnected Dynamics of Hydrology, Biogeochemistry, and Crop Growth
Research Advisor: Dr. Kaiyu Guan
Subsurface (tile) drainage is a critical agricultural practice in the U.S. Midwest, boosting crop yields but also contributing significantly to water quality degradation, a trade-off exacerbated by climate change. This dissertation investigates the interconnected dynamics of hydrology, biogeochemistry, and crop growth in these landscapes to inform more sustainable management. Using a multi-method approach that integrates process-based models, conceptual models, and machine learning, this research quantifies drainage benefits to crop yield and clarifies its role in nutrient export. Key findings reveal that micro-topography drives drainage adoption and that tile systems enhance crop resilience, especially in topographic depressions. However, they also increase watershed nitrogen export through elevated flow rates and nitrate concentrations. Soil oxygen dynamics were identified as a crucial mediator connecting these impacts. This dissertation advances the scientific understanding of tile-drained agroecosystems, providing critical insights for developing strategies that reconcile the dual goals of food security and environmental protection.
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