Studies in vegetable and high tunnel production on the Central Great Plains

Doctor of PhilosophyDepartment of Horticulture, Forestry, and Recreation ResourcesEdward E. CareyA series of four investigations was conducted from 2005 to 2007 focusing on vegetable or high tunnel production. In the first study (chapters 1 & 2), the effect of high tunnels on soil quality was investigated. Grower perceptions of soil quality were assessed from 81 responses to a questionnaire. Indicators of soil quality were evaluated at two KSU research centers. Soil quality was then quantified in high tunnels and adjacent fields at 79 farms, where high tunnels ranged in age from two to fifteen years. Particulate organic carbon as a fraction of soil total carbon was used as an indicator of soil quality. At 80 % of locations, particulate organic matter carbon was greater under high tunnels than adjacent fields. Soil quality was not adversely affected by the continuous presence of high tunnel covering. Management and cropping history in high tunnels was also collected and reported as this information is of interest to growers and the universities and agricultural industries that serve them. Tomato was the most common high tunnel crop. It was grown by 86 % of survey respondents in the previous four year period. Organic soil amendments were applied by 89 % of growers; 35 % use organic soil amendments exclusively. In the second study (chapter 3), two microbial tea solutions were applied to collard green (Brassica oleracea L. var. acephala cv. Top Bunch) or spinach (Spinacea oleracea L. cv. Hellcat) crops at Olathe and Haysville, Kansas, without significant effects on crop yield or soil microbial biomass. Finally, preliminary results from two studies were formatted for reporting as extension publication (chapters 4 and 5). Autumn production, over-wintering, and spring bolting were assessed for 26 spinach cultivars in a 3-season multi-bay Haygrove high tunnel. Also, the effect of autumn planting date on harvest date and yield was observed for two spinach cultivars (cv. Avenger and PVO172) planted on six dates in October and November, under high tunnels at Olathe, Kansas. Spinach planted in the first half of October was harvested in the winter, without loss of spring yield for both cultivars