Annual Medics: New Legumes for Sustainable Farming Systems in the Midwest

Annual Medics: New Legumes for Sustainable Farming Systems in the Midwest

Summary

Rationale:
Annual medics are resource-conserving legumes which are related to alfalfa. They have good
seedling vigor and can be used in cropping systems to smother weeds, supply nitrogen, reduce
soil erosion, and to enhance yield and quality of companion crops and pastures. Because they are
annuals, they provide greater producer flexibility than perennial legumes. The field tests of
annual medics conducted in this study will generate new knowledge useful to producers and
extension agencies.

Objectives:
1) To evaluate annual medic based cropping systems as alternatives to conventional Midwest
cropping systems.
2) To develop educational programs promoting integrated cropping systems that include annual
medics.

Methods:
Research was conducted on-farm and on experiment stations. Eleven on-farm evaluations were
conducted in six states including Illinois, Iowa, Michigan, Minnesota, Ohio, and Wisconsin.
On-station research was conducted in Minnesota, Michigan, and in Wisconsin at the Michael
Fields Institute. Research examined use of annual medics and other legumes as sources of forage,
green manure, and soil cover; as weak smother crops in corn and soybean production systems,
and as contributors of nitrogen.

Results:
Annual medics and berseem clover have potential as emergency forage, crops, green manures,
and cover crops when planted in the spring or following a small grain harvest in summer.
Annual medics have potential into fix up to 150 lb of atmospheric nitrogen per acre and have a
high fertilizer replacement value when used in rotation with corn and canola.

A major emphasis of this project was the use of annual medics as smother crops in corn and
soybean production systems. Annual medics seeded before, simultaneously, or after a corn or
soybean crop was planted were not a consistently effective weed control strategy. Moisture and
temperature conditions had a major effect on medic germination and stand establishment, thus
impeding the medic's ability to compete with weeds. More vigorous medics were able to
effectively reduce weeds, but also had the tendency to compete with companion crops. When
used as the sole weed control strategy, annual medics often resulted in lower grain yields and
economic returns compared to standard crop production practices using herbicides.

Producer Involvement:
This project provided successful interaction of producers with researchers from nonprofit
organizations and universities in the Midwest. Producers were involved in planning, conducting,
and evaluating the research.

Operational Recommendations:
Because medics have not consistently controlled weeds, it is important that producers who are
interested in adopting systems that use annual medics as smother crops limit the number of acres
to which they apply this practice. In addition, there needs to be some type of contingency plan, in
case the medic is unsuccessful.

The use of annual medics as a forage and green manure seems promising, especially for those
producers with canola in their crop rotation.