2019 ASHS Annual Conference

The interest of using high tunnel for extending vegetable production season and enhancing crop yield and quality is growing among organic and local growers in Florida. However, there is a lack of research-based information with respected to integrated nutrient management in organically managed high tunnel systems with sandy soils in the subtropical environment. The objective of this study conducted in Citra, FL was to assess the impacts of summer leguminous cover crop, compost, and organic fertilizer on vegetable performance and nutrient availability taking into consideration crop rotation under organic production in high tunnels. A split-split plot design with 3 replications was used with weedy fallow and cowpea planting prior to the vegetable season in the whole plots, preplant application of solid organic fertilizer vs. in-season fertigation with liquid organic fertilizer as the subplot factor, and application of different types of composts (i.e., yard waste compost, cow manure compost, vermicompost, and no compost) as the sub-subplot factor. Pac choi(Brassica rapa L. cv. Mei Qing) seedlings were transplanted into the high tunnel plots in Oct. 2018 and harvested 32 days later. Spinach(Spinacia oleracea cv. Corvair) was seeded in the same treatment plots 3 days after pac choi harvest without further addition of compost or organic fertilizer. In the pac choi trial, cowpea cover crop did not have any significant effect on crop yield and aboveground nitrogen accumulation. Preplant application of solid organic fertilizer resulted in higher plant dry and fresh biomass in the first two weeks after transplanting, while the fertigation treatment led to significantly greater fresh and dry biomass and nitrogen accumulation in the following weeks and at final harvest. The final yield was significantly higher in the yard waste compost treatment than other compost treatments. However, compost application did not exhibit any significant impact on nitrogen concentration. There was no significant difference among treatments in spinach yield at the first harvest. Yard waste compost resulted in a significantly higher yield than the no compost control at the second harvest and significantly increased the total yield. The pronounced effects of compost application and organic fertilization suggested the need for optimizing organic nutrient management in sandy soils under high tunnel production. The lack of cowpea cover crop effect implied the challenge of using short-cycle leguminous cover crops for meeting vegetable crop nutrient need in high tunnel organic systems, yet, the long-term influence on soil quality and nutrient dynamics deserve further examination.