Effects of High Biomass Cover Crops and Organic Mulches On Soil Properties and Collard Yield Three Years After Conversion to No-till.

Organic producers interested in the adoption of conservation tillage continue to face considerable challenges, particularly with regard to weed control.  Previous work demonstrated that high biomass cover crops in conjunction with organic mulches can provide adequate weed control in a no-till system, but the effects of high biomass cover crops and mulches on soil quality during no-till vegetable production has not been investigated.  The objective of this study was to determine the effects of organic mulches and forage soybean (Glycine max (L.) Merr. cv. Derry) as a summer cover crop on soil organic carbon (SOC), carbon (C) mineralization, total soil nitrogen (N), aggregate stability, and yield in a no-till system without the use of herbicides during limited-input fall collard (Brassica oleracea L. cv. Champion) production in central eastern Alabama.  All treatments, including controls, increased SOC in the 0-5 cm soil depth, indicating that high biomass no-till was more influential on SOC accumulation than the inclusion of summer cover crops or organic mulches.  Treatments did not affect collard yield, which averaged 17,863 kg ha^-1 yr^-1.  Mulches applied at 6.7 Mg ha^-1 yr^-1 did not mineralize nutrients in sufficient quantities to meet collard demands after three years, although the crop appeared healthy.  This research highlights the need for careful nutrient management under limited-input no-till vegetable production.