As one of the most productive and intensive agricultural regions in the world, the Mississippi River basin has experienced profound changes in climate, atmospheric constituents (CO2, nitrogen deposition, ozone pollution), and land use over the past century, and is likely to undergo further rapid changes in coming decades. To meet the food requirement and ecosystem sustainability across this basin, it is important to enhance our understanding of agroecosystem responses (including crop production and environmental consequences) to those multiple global changes. In this study, based on data synthesis and model simulations, we quantitatively assessed the historical variations of crop production and the dynamics of the nutrients/water cycles (greenhouse gas fluxes, runoff, and carbon/nitrogen leaching). We also analyzed the relative contributions of historical multiple global changes. Then we further examined the potential impacts of future climate change and land use under various emission scenarios.
Results/Conclusions
Our major findings show that among those multiple global factors over past century, land use and management practices increased crop production and also largely stimulated greenhouse gases emissions from cropland to the atmosphere which significantly contributed to global warming. Under future high emission scenarios, climate change and land use together would slightly enhance crop production and meanwhile lead to large increases in runoff and total nitrogen leaching, which would alter the hydrology and chemistry of the Mississippi river and then threaten the coastal ecosystem health. This study provides an insight into agricultural production and associated environmental consequences as influenced by multiple global changes, indicating that it is essential to consider the agriculture-water-climate nexus to the solution of food and water security in the Mississippi River basin.