Fig 6. 7-year average of annual (a) water and (b) NO₃-N fluxes at the cropland scale under winter cover crop scenarios over winter seasons (October-March) normalized by the total cropland area.

Note: The SURQ, LATQ, and GWQ in (a) refer to water fluxes delivered to streams by surface runoff, lateral flow, and groundwater flow, respectively. The PERC refers to water percolation entering to groundwater from the bottom of the soil profile. The NSURQ, NLATQ, and NGWQ in (b) refer to NO₃-N fluxes delivered to streams from croplands by surface runoff, lateral flow, and groundwater flow, respectively. The LEA is NO₃-N leaching to groundwater. The PERC and LEA eventually affect the groundwater contribution to streams and NO₃-N loadings in the groundwater flow over time, respectively. The numeric values on the top of the bar graph indicate the reduction amount of water and NO₃-N fluxes under winter cover crop scenarios relative to the baseline scenario. The reduction amount by each pathway is available in S4 Table.