Overflow crowd attends Cover Crops field day
An overflow crowd dodged raindrops to hear the results of cover crop research at Kansas State University on Sept. 9. The Cover Crops field day was held in the Ashland Bottoms west of Manhattan.
The research project is specifically looking at the use of cover crops in no-tillage cropping systems. In typical Kansas cropping systems, cover crops fit between wheat and the next spring grain crop. Winter annual cover crops can be used between two summer crops.
The potential benefits of cover crops include the opportunity to build soil organic matter, reduce soil erosion, enhanced nitrogen cycling, reduce nitrate losses, weed suppression, and reduce disease inoculums. Drawbacks to cover crop usage include wet or delayed planting due to heavy residue, slow growth of the following crop due to heavy residue, nitrogen tie up, cover crops becoming weeds, and increased disease inoculums.
In addition to finding out which cover crops work best in Kansas no-till scenarios, the study is also looking at the effect on soil structure and weed suppression.
"We are looking at the effect on soil properties of an extra crop after wheat," DeAnn Presley, K-State soil scientist, said. "More soil organic matter means better water infiltration."
Anita Dille, K-State Research and Extension weed ecologist, has received a USDA grant to study the use of cover crops to suppress weeds. The study will look at what producers can do to combat weeds in an integrated way. Pearl millet is a cover crop species that has good weed-smothering ability and has high organic matter. Oats, Berseem clover, forage soybeans, and triticale all offer varying degrees of weed suppression.
Justin Petrosino, K-State graduate research assistant, said established cover crops and high levels of residue left by cover crops could significantly reduce weed emergence. Cover crops can reduce a weed's biomass and consequently reduce its ability to produce seed. A burn-down is required if weeds are already established.
"Clean up weeds before cover crops are planted, to give cover crops a jump on the weeds," Petrosino said.
Kevin Arnet, K-State graduate student assistant agronomy, gave an overview of the cover crop species used in the no-till cropping systems at the Ashland bottoms field site. The study included canola, winter peas, sorghum sudangrass, and forage soybeans, double crop soybeans, and then compared these to chemical fallow. They also planted a mix of cover crop species in one plot.
There are some advantages to using a mix of cover crop species, according to Arnet. For example, deep-rooted cover crops could be used with shallow-rooted cover crops to make better use of water and resources; combining high C to N ratio species with plants that have low C to N ratio can influence mineralization of cover crop residues; and a large spectrum of weed control may be possible with a mixture of cover crops. Arnet said allelopathic suppression of weeds has been shown to be species specific.
Before planting a crop after wheat, producers need to consider the key economic factors. Kevin Dhuyvetter, K-State Extension farm management specialist, said these economic factors include the price of seed, crop yield, value of nutrients removed or credited, cost of planting and harvesting the crop, impact on yield following the crop, and impact of costs of the following crop. Dhuyvetter said producers can plant a crop after wheat as an additional cash grain crop, as an additional forage crop to graze or bale, or as a cover crop to increase residue, to improve soil quality, to fix nitrogen for the next crop, or to suppress weeds.
When using a cover crop after wheat, the seed is the largest proportion of the cost. Normally 40 percent of the cost of a cover crop will be the seed purchase. As seed costs decrease, positive economic returns will be realized at lower nitrogen and commodity prices, Dhuyvetter said. Producers need to consider the cost of chemical fallow versus establishing a cover crop, the possible nitrogen credit for the following crop, and the impact on yield of the following crop.
"Cost control is important when planting a cover crop," Dhuyvetter said.
Many of these same field trials were repeated at the experiment field near Hesston, Kan.
Doug Rich can be reached by phone at 785-749-5304 or by e-mail at email@example.com.