In the field of environmental science and water quality, there is a growing recognition of the importance of understanding the complex redox dynamics of inorganic nitrogen species within the vadose zone. The vadose zone, which extends from the surface to the groundwater table, plays a crucial role in buffering and influencing the fate of contaminants before they reach the groundwater. Nitrate, in particular, is a significant groundwater contaminant in heavily cultivated areas such as Nebraska. However, studying the vadose zone and preventing nitrate contamination is a challenging task that requires a meticulous examination of the redox reactions governing the transformation of nitrogen species in a controlled environment. These processes are fundamental to the cycling of nitrogen, the overall health of ecosystems, and the quality of water resources. By investigating the interplay between biological, chemical, and physical factors, we aim to unravel the mechanisms behind nitrogen transformation and shed light on their implications for groundwater contamination and the sustainability of ecosystems. To achieve this, our study conducted a laboratory-scale experiment using undisturbed soil sediments carefully packed in columns to simulate the vadose zone of the corn-planted and sprinkler-irrigated fields in Central Nebraska. These columns were divided into two groups based on irrigation methods, namely sprinkler irrigation and rainfed, to replicate the diverse moisture regimes observed in agricultural settings. Our study was conducted without the addition of external nitrate, ensuring that we focused solely on the transformation of legacy nitrogen within the vadose zone under different irrigation systems. In this seminar, we will present findings from our experiment, which used a modern and unique research experimental design and shed light on the intricate redox transformation of inorganic nitrogen species in the vadose zone.

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