Effect of Rapeseed and Cereal Rye Used As Cover Crops on Soil Health in Organic Sweet Potato Production.

Sweet potato (Ipomoea batatas (L.) Lam.) is an important food crop, and in recent years, there is an increase in sweet potato consumption and a demand for organically produced sweet potatoes. Organic sweet potato growers however, are challenged by sustainable soil management, which impacts the occurrence of soilborne disease, weed competition, and other pest issues that consequently reduce tuber yield and/or quality. This research aimed to develop a strategy of using cover and/or green manure crops for improving soil health, as well as reducing disease and weed competitions. A field experiment was conducted at a Certified Organic Producer’s field located in Marshall, Missouri. Treatments, including use of rapeseed (Brassica napus L.) or cereal rye (Secale cereale L.) as cover or green manure crops were arranged as a split-plot in a randomized complete block design with three replications. The whole-plot variable was the use of plant species as either cover or green manure, in addition to a control without any cover crops, and the sub-plot variable was the crop species. After the establishment of cover crops in fall 2016, plots were monitored regularly for presence of weeds and soil volumetric water content. Soil health was assessed by determining soil organic matter, pH, nutrients, and soil microbial population and composition by detecting phospholipid fatty acid (PLFA) analysis prior to cover crop establishment and prior to transplanting of sweep potato slips. After sweet potato harvesting in October 2017, soil health will be determined for the parameters described above along with sweet potato yield. This is an ongoing experiment, and detailed results will be discussed in the presentation.