Cover crops can greatly benefit your farming operation, but they require “many considerations” before making that optimal selection, according to Kansas State University Extension researchers Anita Dille and DeAnn Presley. The two recently tackled this subject in K-State’s “eUpdate” newsletter.
“[Here] are some questions to guide you when considering cover crops for your field, with weed management as a goal,” they write.
1. What are the potential benefits and costs of cover crops?
Most producers are aware of the various benefits that cover crops can deliver – from reduced erosion to protecting nutrients in the soil or even acting as a barrier to would-be weeds.
But Dille and Presley urge farmers to be aware of the costs associated with cover crops, too. That includes seed cost and equipment to plant, the potential for the crop to turn into volunteer weeds, and the possibility that the timing and ability to terminate the crop could prove inconvenient.
2. How will you plant it, and when?
“Consider the crop rotation that you have planned and determine the best time to seed and establish the cover crop,” Dille and Presley note. “For the greatest weed management benefit, know when the key weed species you are targeting germinate and emerge. Establish the cover crop prior to that key point in the lifecycle of the weed for most impact.”
3. How can cover crops help control weeds?
Dille and Presley say there are several ways cover crops control weeds. They compete for light and water resources, for example. And some cover crops even release chemicals from their roots or decaying residue, which can further inhibit weed seed germinations, they say.
4. What will precede and follow the cover crop in your rotation?
“Some cover crops tie up nitrogen, so it is important to consider the carbon-to-nitrogen ratio of the cover crops being considered,” the researchers note. “This will influence the rate of residue breakdown and future release of nutrients in the subsequent crop.”
Also look into what pre-emergence herbicides you used this spring – some can persist into the fall and impact cover crop establishment.
5. How will you terminate your cover crop?
Some cover crops die naturally during the winter, like mustards, peas and spring cereals. Other crops could require a properly timed spring burndown. Know what you’ll have to spray and when, and if a roller or crimper will be effective on your cover crop. For example, a roller/crimper is not effective on clovers, according to Dille and Presley.