Soil Erosion and Nutrient Runoff in Corn Silage with Kura Clover Living Mulch and Winter Rye.

Corn (Zea mays L.) is a productive and popular forage crop that can exacerbate soil loss, surface water runoff, and nonpoint source nutrient pollution from agricultural fields.  The objective of this research was to compare the effects of using kura clover (Trifolium ambiguum M. Bieb.) living mulch and winter rye (Secale cereale L.) in corn silage production on runoff, soil physical properties and organic matter, and forage yields at the University of Wisconsin Lancaster Agricultural Research Station 8 km west of Lancaster, WI (42°50' N, 90°48' W, 300 m above sea level).  On loess derived Fayette silt loam (fine-silty, mixed, superactive, mesic Typic Hapludalf) with slopes of 8 to 15%, during simulated, short, heavy rainstorms, kura clover living mulch reduced water runoff by 50%, soil loss by 77%, and P and N losses by 80% relative to monocrop corn.  Rye reduced water runoff by 67%, soil loss by 81%, P loss by 94%, and N loss by 83% when planted after corn silage harvest.  When rye was planted following corn silage in kura clover living mulch, water runoff was reduced by 68%, soil loss by 77%, P loss by 94%, and N loss by 84% relative to monocrop corn.  Dissolved reactive P, NH₄-N, and NO₃-N losses in runoff were often, but not always, higher in monocrop corn.  Treatment differences in nutrient losses were primarily due to differences in runoff amount rather than concentrations.  Higher ground cover, soil aggregate stability, and soil organic matter, as well as soil surface disturbance from rye planting, were associated with improved infiltration and reduced soil and nutrient losses in the cover cropped treatments.  When grown in kura clover living mulch, both corn and rye had lower yields but this was offset by lower fertilizer requirements and improved farmland and environmental function and quality.