Saturday, February 15, 2014

Cover Crops and Conservation Tillage Improve Sweet Potato Production

Sweet potatoes. Southern SARE archivesCandace Pollock (
Incorporating winter cover crops in sweet potato production may save farmers input costs, as well as improve soil fertility, increase land use efficiency, and help control insects.
Ramon Arancibia, a horticulturist with the North Mississippi Research and Extension Center at Mississippi State University, received a Southern Sustainable Agriculture Research & Education (SSARE) grant to study winter cover crops as a low-cost, environmentally friendly practice for farmers interested in sustainable agriculture or who are looking for an alternative to conventional production.
Arancibia collaborated with University of Arkansas-Pine Bluff to work with farmers in Mississippi and Arkansas for on-farm trials.
“The idea behind the project was to promote stewardship in the production system, and to find ways to reduce costs associated with land preparation, fertilization and insect control,” said Arancibia. “Among the main problems expressed by sweet potato farmers in Mississippi are the lack of effective methods to control soil insects and nematodes, and high production costs, specifically labor costs. The issues for Arkansas farmers were similar, and they expressed a lack of resources on sweet potato production technologies that are adapted to their needs.”
In the SSARE Research & Education grant, “Developing Low-Cost Sustainable Sweet Potato Production Strategies to Facilitate Adoption in the Mid-South,” selected winter cover crops along with a control fallow treatment were evaluated for three years on their effect on summer sweet potato production both in a conventional and no-till system. The cover crops were selected based on their potential advantages in suppressing nematodes and weeds, attracting beneficial insects and on their role as a source of nitrogen. The crops chosen included wheat, ryegrass, crimson clover, hairy vetch, mustard, and radish.
“Legumes planted in early September resulted in biomass production of 4-6 tons per acre compared to a later November planting, which resulted in 1-2 tons per acre. Legumes, radish and rape produced consistently more biomass than the weedy fallow,” said Arancibia. “Legumes and radish were the best biomass producers. This is useful information for sustainability of sweet potato since it requires 40 to 60 pounds/acre of nitrogen and legume cover crops may provide 60 to 150 pounds/acre of nitrogen depending on biomass production.”
The radish cover crop performed the best at suppressing nematodes and insect pests, in addition to loosening the soil. Loose soil, said Arancibia, is required for proper and marketable sweet potato root shape.
While yield measurement wasn’t a specific goal of the study, Arancibia found that, overall, sweet potato production following a winter cover crop produced comparable yields in both a conventional and no-till system compared to fallow treatment. In some cases, yields were higher.
“Our results suggest that cover crops and conservational tillage may help in soil conservation and improvement, and in reducing production costs without sacrificing yield,” said Arancibia.
The most successful aspect of the grant project was farmer adoption of cover crop systems as a result of the farmer’s involvement in the study. Many of the growers involved in the study found that cover crops improve soil quality and suppress insect populations.
Arkansas grower Stephan Walker discovered that sweet potatoes yielded well behind a cover crop, insect populations were very low, and fewer nutrients were required after a cover crop.
As a participant in the cover crop project, “I feel that valuable information was gathered,” said Walker. “I recommend that these types of demonstrations be done again, whenever the opportunity arises.”
Arancibia said that studies on cover crops will continue, including how cover crops affect the incidence of soil-borne diseases and how cover crops change biology to improve soil health.
Additional project collaborators include William Burdine, MSU Extension agronomist; Fred Musser, MSU assistant professor; Mark Shankle, MSU associate research professor; and Obadiah Njue, University of Arkansas-Pine Bluff Extension horticulture specialist.
For more information on the SSARE-funded project, visit the national SARE database and search by project number LS09-215.
Published by the Southern Region of the Sustainable Agriculture Research and Education (SARE) program. Funded by the USDA National Institute of Food and Agriculture (NIFA), Southern SARE operates under cooperative agreements with the University of GeorgiaFort Valley State University, and the Kerr Center for Sustainable Agriculture to offer competitive grants to advance sustainable agriculture in America's Southern region.