The Effects of Cover Crops on Vegetable Yield and Mineral Nitrogen in High Tunnel Agricultural Systems
High tunnels, greenhouse-like structures which rely primarily on solar heating, allow farmers to extend the growing season. However, the intense crop rotation and agricultural practices that accompany growing cash crops year-round in these tunnels can cause problems for soil health and fertility and potentially affect cash crop yield. Cover crops may represent a sustainable solution to help maintain soil health and crop yield within these agricultural systems. In our high tunnel, cover crops were planted in late May followed by the cash crop, spinach, in Fall. We compared the effects of a legume cover crop (cowpea) and a mixture of legume and non-legume cover crops (cowpea and sorghum-sudangrass) on cash crop yield and mineral nitrogen. We expect that the spinach yield and mineral nitrogen levels will be higher where only the cowpea cover crop was planted, due to its potential to form symbiotic relationships with nitrogen fixing bacteria in the soil and the importance of nitrogen for plant health and development. Further, if there is a positive relationship between measured mineral nitrogen in the soil and spinach yield, it will show that mineral nitrogen may be a good indicator of soil fertility for future cash crop production.