NOVELTY, Mo. - With significant crop yield reductions across Missouri and much of the Midwest, lots of nutrients and herbicides remain in the soil, having never been absorbed by drought-stricken corn and soybean plants. This presents opportunities and challenges for farmers looking to plant cover, winter or forage crops this fall.
Kevin Bradley, associate professor in the Division of Plant Sciences in the University of Missouri College of Agriculture, Food and Natural Resources (CAFNR), offered guidance to producers at Greenley Research Center's annual field day, Aug. 7.
First and foremost, check labels, Bradley said. Several factors will influence herbicide carryover, including the type of herbicide applied, rate applied, time it was applied, the soil pH and rainfall since the initial application.
In fields where uncertainty of carryover is high, Bradley recommends farmers conduct a soil bioassay before sowing their fields. Farmers should gather soil samples from across the field in question several weeks before they intend to plant their fall crops, mix the samples together and plant their seeds into pots to evaluate whether there's any indication of herbicide carryover injury.
It's important to have a control sample as well. Farmers should use soil from a plot where there is no concern with carryover for the control. This simple test can help farmers avoid the loss of wheat, forages or other crops they'll plant in the coming weeks. Bradley provided a chart detailing the replant interval for winter wheat and forage grasses following dozens of herbicides used in Missouri. (See "Consider Herbicide Carryover Potential before Planting Wheat or Forage Grasses this Fall" at http://ipm.missouri.edu/IPCM/.)
For farmers like Winford Vaughn, that information is critical. Vaughn grows corn and soy near Edina, Mo., and often plants rye as a cover crop, or plants winter wheat.
Sowing new seeds
In addition to hearing about dealing with drought, Vaughn said he was intrigued by several of the ongoing studies at Greenley. "I found the tillage radishes very interesting too. I want to take care of my soil and the radish interested me a lot for that purpose," Vaughn said. "I'm a firm believer in putting organic matter back in the soil, and I've seen the results."
Leah Sandler, a graduate student in plant sciences, discussed the potential for using tillage radish as a cover and grazing crop. In 2012, it showed promise for weed suppression, soil aeration and as supplemental forage. Sandler shared preliminary results from the first year of the study.