2018 ASHS Annual Conference

Reduced tillage systems for vegetables must provide good crop establishment, soil temperatures, moisture and fertility to support desired quality, yields and timeliness of harvest. In more northern climates, zone tillage vegetable systems have shown to balance some of the soil improving benefits of no-till with the well-known advantages of tillage. However, zone tillage must overcome multiple barriers to grower adoption, including high weed pressure, interference from surface residue, and low soil nitrogen (N) availability. Strip planting legumes (in-row) and winter rye (between-row) could advance zone tillage systems for summer transplants by concentrating low residue, high nitrogen in the tilled zone while maintaining high-residue, weed suppressive mulch between-row. Over 4 site-years, we have investigated the effects of overwintering legume cover crops (none, hairy vetch or crimson clover) grown in mixture with cereal rye on N availability, weed suppression, and crop yield in an organic strip-tilled cabbage system. Cover crops were planted in the fall at two locations (NY and MI) in both mixes and alternating strips of legume and rye. In spring, cover crops were then managed by flail mowing, retained on soil surface and zone tilled. We measured cover crop biomass and total N and C:N ratio, weed biomass prior to planting, soil inorganic nitrogen at planting and during crop growth, and weed biomass at harvest and crop yield. Supplemental sidedress N was applied to subplots for each treatment. Winter rye – vetch mixtures had similar total cover crop biomass and total N compared to crimson clover but significantly lower C:N ratio. Optimizing cover crop termination with mowing was challenged by differences in species maturity; crimson clover was terminated later than ideal, since mowing had to match cereal rye anthesis. Strip planted cover crops facilitated zone-tillage by minimizing residue in the zone. Strip planting did not, however, result in yield improvements compared to mixed cover crop planting. Sidedress N provided slight improvement in yield within each cover crop treatment, but did not change ranking of the cover crops.