Surface water quality and cropping systems sustainability under a changing climate in the Upper Mississippi River Basin

摘要: Agricultural nonpoint source pollution is the main of nitrogen (N) and phosphorus (P) in intensely row-cropped Upper Mississippi River Basin (UMRB) stream system considered primary cause northern Gulf Mexico hypoxic zone according to US Environmental Protection Agency. A point crucial importance this region therefore how intensive corn (Zea mays L.)-based cropping systems for food fuel production can be sustainable coexist with a healthy water environment, not only under existing climate conditions but also changed future. To address issue, UMRB integrated modeling has been built greatly refined 12-digit subbasin structure based on Soil Water Assessment Tool (SWAT) quality model, which capable estimating landscape in-stream pollutant yields response wide array alternative and/or management strategies climatic conditions. The effects following four agricultural scenarios crop loads exported from cropland streams rivers were evaluated: (1) expansion continuous across entire basin, (2) adoption no-till all soybean (Glycine max L.) fields region, (3) substitution traditional corn–soybean rotations an extended five-year rotation consisting corn, soybean, three years alfalfa (Medicago sativa L.), (4) implementation winter cover within baseline rotations. each scenario evaluated both current projected midcentury (2046 2065) General Circulation Model (GCM). All behaved similarly historical future climate, generally resulting reduced erosion nutrient loadings surface bodies compared management. Continuous was resulted increased N while most environmentally effective able sustain at almost same levels. Rye (Secale cereale fallow period reducing sediment-bound soluble forms nutrients. results indicated that practices could reduce sediment, N, P exports by up 50% without significantly affecting yields. Results change showed effectiveness strongly linked availability predicted assisted mitigating transport, although small loss production.