Cover Crop, Nutrient Amendment, and Crop Cultivar Affect Organic Cucumber and Tomato Production Systems In the Great Lakes Region

Incorporation of cover crops, integrated nutrient and pest management strategies bear paradigm importance under organic production systems. Our study tested the use of cover crops (cereal rye alone or a mixture of rye and hairy vetch), dairy compost, monoculture, polyculture (growing alternate rows of cucumber and tomato) and crop varieties with relevance to crop yield, fruit quality and soil microbial population under organically managed cucumber and tomato production systems. The two cucumber and tomato cultivars tested were ‘Dasher-II’ and ‘Cobra’, and ‘Big Beef’ and ‘Mountain Fresh’, respectively. There was no statistical difference and no interaction between variety and treatment for cucumber. Cover cropping with rye + vetch + compost combined with polyculture had the highest cucumber yield (18.8 kg/12 plants). The cucumber monoculture system did not perform well, primary because of higher cucumber beetle infestations and disease incidence (bacterial wilt).  Observations from current study hint towards a potential use of polyculture as a crop insurance tool against cucumber beetles and other pests that pose a phenomenal threat to organic cucumber production in our region.  There were significant interactions between tomato cultivars and the treatments.  Higher yields were obtained from rye + vetch + compost treatments. Marketable yield for ‘Big Beef’ and ‘Mountain Fresh’ were 84.8 and 57.9 kg/12 plants, respectively. Both monoculture and polyculture treatments that received compost produced similar marketable yields. Compost treatment under rye cover crop exhibited the highest microbial biomass (197 µg C/g soil after 7-day incubation). Plots which did not receive compost showed the lowest values. One of the biggest challenges experienced in this study was the ability to establish a decent stand of hairy vetch. With the unpredictable weather in the great lakes region, planting of hairy vetch late in the season after a tomato crop might not always provide enough time for the vetch to grow and accumulate sufficient biomass before winter.  This leads to high mortality of hairy vetch when the seedlings are too young and cannot withstand the harsh winter.  Therefore, for effective integration of hairy vetch into crop rotations in our region, hairy vetch should follow a crop with a shorter growth cycle than tomato.  We found that integrating a cover crop mixture of cereal rye and hairy vetch supplemented with a sound nutrient management program (compost) is an effective way to stabilize yields, improve soil fertility, and build up a healthy soil for sustained crop production.