Even though the drought conditions over most of the region have made it a difficult year for many row crop producers, the coming change in the season should have farmers thinking about what comes next.In the Southeast, that often means cover crops.
Cover crops are usually winter annuals planted in the fall, allowed to grow through the winter and spring and then terminated close to the time of planting of the following row crop. Cover crops can be grass or legume species, and in this region the most common species used are wheat or cereal rye.
According to Dr. Donald Tyler, professor of soil science with the University of Tennessee Institute of Agriculture Department of Biosystems Engineering, the two legumes recommended in Tennessee are crimson clover and hairy vetch. Both types of cover crops have advantages and disadvantage in row crop production. “Ideally, cover crops are planted using no-tillage in previous crop residue,” Tyler said. “Cover crops can offer a number of advantages when properly managed in row crop systems.”
Tyler lists these as the chief advantages:
• additional soil cover, which is especially useful in systems such as non-rotated cotton, which leaves limited residue on the soil surface even in continuous no-tillage.
• additional carbon sequestration. While the cover crop is growing in the fall, winter and spring it also captures additional carbon. This can result in more rapid increases in soil carbon storage in no-tillage systems.
• enhanced biodiversity of soil organisms such as bacteria and fungi.
Grass cover crops tend to make more fall growth than legumes when planted after crop harvest. Tyler notes that this is especially true when following cotton, which, in most cases, is harvested later than corn or soybeans. “The grass covers will provide more winter erosion protection on highly erodible land than is usually the case with the winter annual legumes,” Tyler said.
The soil expert also explained to the Milan crowd that legumes offer other distinct advantages as a cover crop, including fixation of atmospheric nitrogen while growing. “Part of this nitrogen is recycled to the following row crop as the legume cover crop residue decomposes. We recommend that if either crimson clover or hairy vetch is allowed to grow to mid-bloom before termination and subsequent row crop establishment, then nitrogen application can be reduced by 60 to 80 lb N/acre for a number of crops, including corn and cotton,” said Tyler. “The reduction depends on aboveground biomass accumulation, which can be related to initial stand establishment, growing conditions, etc.”
Tyler added that biomass accumulation can be enhanced in some situations by mixing grass and legume species. He cautions, however, that mixtures are more costly and in some cases are more difficult to manage in the following row crop.
Cover crops costs include seed, establishment and in some cases additional burndown costs. Tyler said cost share programs offered by the Natural Resource Conservation Service can help offset some of the cover crop expenses.
“Cover crops do cost money, time and management,” said Tyler. “If they can be properly managed in the crop system, they can provide a number of soil quality and environmental benefits, and in some cases result in higher yields and greater profitability.”
For more information about cover crops, contact the Cannon County Extension office 563-2554 or visit http://www.utcrops.com. All programs of the University of Tennessee Extension are open to all interested persons. UT Extension provides equal opportunities in programs.
