Eutrophication of surface water bodies is a global issue that is driven by elevated phosphorus losses in freshwater systems. In many regions, these elevated nutrient loads are contributed by agricultural practices. Field and watershed nutrient losses are driven by runoff processes, which may vary temporally with climate drivers, spatially across physiographic zones or ecoregions, or with different production systems. Within any system, nutrient fluxes are ultimately driven by the interaction of supply and transport mechanisms, which can lead to hotspots and hot moments for elevated nutrient losses in agricultural systems. Understanding these mechanisms and their interactions across a range of scales and systems can provide insight into the viability of solutions for mitigating both contemporary and future water quality challenges. Linkages between hydrology and nutrient sources across northern temperate agricultural regions in North America will be discussed, and the significance of climate and landscape drivers on phosphorus losses will be demonstrated. Drawing on studies from a suite of field observatories, the employment of selected conservation practices (no-till, cover crops, nutrient management) to disconnect supply and transport mechanisms through will be highlighted.
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