A multiregional analysis of hairy vetch cover cropping as a driver of ecological nutrient cycling in organically managed high tunnels

Abstract

The use of high tunnels (HTs) in vegetable production has expanded across the United States, but heavy use of nutrient amendments presents soil health challenges. Legume cover crops may be an alternative for supplying N and supporting soil biological activity. Our objectives were to (1) assess cover crop productivity in HTs across a multi‐state climate gradient, (2) measure cover crop effects on soil N pools and biological activity, and (3) quantify cover crop impact on tomato ( Solanum lycopersicum L.) productivity. A 3‐year experiment was conducted in Kansas (KS), Kentucky (KY), and Minnesota (MN) to assess hairy vetch ( Vicia villosa Roth) productivity in HT environments and determine the effects of a tomato‐hairy vetch HT rotation on tomato yields and soil health parameters (total C and N, permanganate oxidizable C, nitrate, potentially mineralizable N, microbial enzyme activity, and microbial biomass) in comparison with non‐cover‐cropped standard practices. Vetch biomass ranged from 1057 to 4151, 220 to 1364, and 1971 to 2870 kg ha ⁻¹ in KS, KY, and MN, respectively. Hairy vetch cover cropping reduced soil nitrate concentrations during the tomato season at KS and KY. Although the significance of effects was inconsistent across sites and timepoints, organic N and C pools and enzyme activity tended to be higher in the vetch rotation than the control. Tomato yields and marketability were similar between treatments. Our findings indicate that hairy vetch cover cropping has potential to increase long‐term soil fertility in HTs while mitigating the potential for nitrate loss and maintaining tomato productivity, but more research is needed to provide agronomic guidance for ensuring consistent cover crop stand establishment and productivity.