2012 Sweet Potato Variety Trial

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We located the 2012 sweet potato trial at the Cannon Horticulture Project site on the Kerr Center Ranch. The Project was established in the fall of 2007 and achieved certified organic status in June 2011. The Cannon site features a loam soil with moderately-poor drainage. This is not considered good soil for sweet potatoes; they do best in light, well-drained sandy loams. However, the Cannon site has organic matter levels around 3.1% and excellent pH that ranges from 6.6 to 7.0. While native phosphorus and potassium levels on these soils are low, compost applications in 2009 improved the phosphorus status considerably, and potassium moderately.
Prior to sweet potatoes, the trial plot was planted to a winter cover crop of grain rye, and crimson and arrow leaf clovers. The previous crop in 2011 was a blend of annual sorghums, with a small amount of buckwheat, grown as green fallow. Field preparation began in early April by mowing the winter cover crop and disking twice. On May 10, planting ridges were prepared first by rototilling, using a BCS-mounted tiller. It was followed by ridge construction using a Hoss Wheel Hoe, mounted with hilling plows. Ridge spacing was 48 inches.
We transplanted the entire trial of twelve varieties on May 24. Each plot was 20 feet long, with 20 plants per plot and one-foot spacing between plants. The plots were replicated three times.
Beginning with the date of transplanting, we provided supplemental drip irrigation throughout the season as needed. None of the varieties showed particular heat stress; no foliar diseases were observed, and though there was some damage by striped blister beetles, it was not significant. Weeds were managed by a single cultivation on June 6 using wheel hoes. On June 7, the inter-row areas were seeded to buckwheat as living mulch to suppress weeds and attract beneficial insects. No additional weed control was required.
We hand-dug the roots on October 2 and 3. Marketable roots from all varieties were cured, and weighed.

George Kuepper
Luke Freeman
Kerr Center for Sustainable Agriculture