Alden Braul

M.Sc. Advisor: Dr. Martin Entz
University of Manitoba

Thesis Summary:

The Potential of Black Medic (Medicago lupulina) as a Self-regenerating Legume Cover Crop

Many organic farmers have experience using black medic as a self-regenerating legume cover crop. This permanent association between black medic and the grain crop adds organic nitrogen to the nutrient pool, increases grain protein levels, and provides excellent ground cover. Understanding the benefits of the system and the pattern of recruitment of black medic is the focus of several field trials at the University of Manitoba.

Black medic recruitment from the soil seed bank is controlled by a hard seed coat which makes the seed impermeable to water, thereby preventing germination. Fracturing the seed coat happens during the freezing temperatures in winter, and also during temperature fluctuations under moist conditions in the spring and summer. This allows black medic to produce seedlings at almost any time during the spring and summer period. The field trials in Indian Head SK, Carman MB, and Winnipeg MB are designed to measure the impact of crop type, tillage system, nitrogen fertilizer application, and general environmental conditions on the recruitment pattern of black medic.