2018 ASHS Annual Conference

The environment without rainfall, limited space, and potential climate control in a high tunnel calls for sustainable crop and soil management approaches. With high tunnel production primarily dominated by tomatoes and the potential to grow crops year-round, a cohesive and focused approach is needed to tackle issues that would arise due to continuous crop production under these structures. Some common issues experienced include high salt build up, resurgence of soil-borne and foliar diseases, poor soil structure, lack of microbial diversity, and reduced crop yields. One of the strategies to mitigate these issues would be include cover crops in high tunnels. This study conducted in a 9.1 m x 29.2 m high tunnel for two years at the Horticulture Research Station, Ames, Iowa comprised of three treatments – oilseed radish, yellow mustard, or no-cover crop. Tomato ‘Mt. Spring’ was transplanted after cover crop termination each year. The experimental design was a randomized complete block design with four replications. Each treatment plot was 3.1 m wide and 6.1 m long with a 1.2 m buffer between the blocks. The study investigated the effect of cover crops on weed biomass, tomato growth characteristics, soil properties, and tomato yield and quality. Cover crop biomass ranged from 3362 to 4483 kg^.ha^-1. There were no statistically significant differences in soil pH at any of the sampling dates. Soil electrical conductivity showed significant differences at the start of the experiment but those differences gradually evened out. Plant height and width measured in the month of July in both years did not show any difference. Cover crops significantly decreased weed biomass when compared to no-cover crop treatment but there were no differences between cover crops. There were no statistically significant differences in marketable or non-marketable tomato yields between treatments. To observe positive changes in soil properties and crop yield, due to cover cropping, requires continuous cover cropping for extended period of time. Longer term studies are needed to document the impact of cover cropping in high tunnels on soil quality and health. Integration of cover crops in high tunnels has the potential to build soil organic matter, improve soil quality and health, and serve as a crop rotation tool.