Legume cover crops in high tunnels: Field evaluation for soil health and controlled environment freezing tolerance

Abstract

This thesis explores legume cover crops as a possible management tool for nitrogen fertility and soil health maintenance in high tunnels. Projects include: 1) a two-year field evaluation of three fall planted cover crop mixes for winter annual production, 2) a controlled environment freezing tolerance study of hairy vetch (Vicia villosa) and red clover (Trifolium pratense) using simulated high tunnel conditions, and 3) a one-year field evaluation of three spring planted cover crop mixes. Cover crop mixes used in projects 1 and 3 consisted of: a) red clover monoculture (T. pratense), b) Austrian winter pea/winter rye 1:1 biculture (Pisum sativum and Secale cereal), and c) hairy vetch/tillage radish/winter rye 4:1:15 mix (V. villosa, Raphanus sativus, and S. cereal). Winter annual legume results show a wide range of biomass nitrogen additions (19.7 to 365.0 kg N ha-1), with no negative impact cash crop yield or soil health measures.