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.
During 2010 and 2011 we compared the effects of 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 we simulated short, heavy rainstorms on loess soils with 8 to 15% slopes.
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.
Most of the differences between cropping treatments were 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.
Our short-term objectives, to document the environmental effects of kura clover living mulch and winter rye in no-till corn silage on surface runoff was was completed during 2011. The results were published as a Master’s thesis, presented as a seminar in Madison at the University of Wisconsin campus for an audience of professors, research staff, and graduate students, and shared with research station staff in southwestern Wisconsin.
The research is being submitted as a poster presentation at the 2012 Agronomy Society of America conference and will be submitted for peer-review publication as well.
Research in forage production systems incorporation kura clover living mulch is ongoing at the University of Wisconsin and accessible cropping systems will be promoted through direct communication with extension agents and as a brochure detailing both the agronomic management and environmental benefits of kura clover living mulch.