Impact of Changes in Land Use and Land Management on Nitrogen Loading Within the Continental United States

Excessive nitrogen loading degrades water quality and thereby impacts human and ecosystem health. Previous work has shown that nitrogen loading to streams is influenced by nitrogen inputs to watersheds, by land use, and by the amount and intensity of precipitation. In addition, climate-change induced changes in precipitation patterns alone have been shown to have the potential to significantly increase future nitrogen loading within the continental United States. Although future socioeconomic changes will also affect land use and land management, the impact of these changes on nitrogen loading is not well understood, however. Here we examine the impact of changes in land use and land management for six socioeconomic pathways developed for the Coupled Model Intercomparison Project Phase 6 (CMIP6). Preliminary results suggest that future societal choices will substantially impact riverine total nitrogen loading for the continental United States, and that changes in cropland area, urban area, and fertilizer application rates will all contribute to these changes. These findings highlight the need to account for the impact of societal trends in designing strategies for managing inland and coastal water quality.