The 2011 ASHS Annual Conference

Vegetable production requires adequate amounts of plant available soil nutrients to meet plant growth and yield requirements. In an on-going four-year field experiment, various winter and summer cover crops (CC) were evaluated for their effects on vegetable productivity, nutrient cycling, and weed management.  Three winter (hairy vetch, mustard or rape, winter wheat) and three summer (chickling vetch or bean, buckwheat, proso millet) cover crops (9 treatment combinations) were evaluated for modifying the short-term nitrogen (N) availability of soils when growing organic snap beans, broccoli, and sweet corn.  Average soil mineral (0–15 cm) N varied by as much as 40% depending on the winter-summer CC combination.  Highest N levels were measured in the hairy vetch-millet or hairy vetch-buckwheat when taken 5 weeks after bean and sweet corn emergence (early July).  Rape-Buckwheat and Wheat-Buckwheat CC had intermediate levels of soil mineral N.  In contrast, rape-chickling vetch and wheat-chickling vetch had the lowest soil mineral N levels.  Soil mineral N levels were highly correlated to bean, broccoli and sweet corn productivity levels and biomass production of the different CC.  Plant stands were unaffected by CC combination.  However, yield of all vegetables were greatest in the hairy vetch-millet or hairy vetch-buckwheat combinations and lowest in the rape-chickling vetch and wheat-chickling vetch CC’s.  While productivity levels are still considered low, year to year improvements are noted with CC that produce higher amounts of biomass.