As the end of corn harvest nears, some producers will soon be turning their cattle into corn stalks or cover crops to graze. Before taking this step, take time to review the labels from in-season and fall-applied herbicides for any grazing restrictions. These restrictions can also be found on pages 182-185 in the 2016 UNL Guide for Weed, Insect, and Disease Management (distributed at the 2016 Crop Production Clinics) or in this table from the forthcoming 2017 Guide. The forage, feed, and grazing restriction only applies to the crop for which the herbicide was applied.

When it comes to grazing cover crops planted into these residues, one must check the replant/rotation restriction guidelines found on the herbicide label and also on pages 168-181 of the 2016 UNL Guide for Weed, Insect, and Disease Management.

If the label doesn’t specify any restrictions, grazing should be fine. If you want to be on the safe side, chemical representatives often recommend using the pre-harvest interval for the amount of time to wait before grazing stalks.

Some labels will specify that residue should not be grazed or baled and fed to livestock. Sometimes studies were conducted to identify potential safety concerns. In other cases, the chemical company may not have conducted all the studies required by the Environmental Protection Agency (EPA) due to high testing costs. If that’s the case, the EPA requires the strongest restrictive language be placed on the label. Regardless, if it says there’s a grazing restriction on the label, the label needs to be followed as it is a legal document and the law.

For some producers another concern may be the amount of green volunteer soybeans they’re seeing due to harvest losses from weather-related soybean shattering. Before grazing, be sure to check for any herbicide grazing restrictions from herbicides applied in-season to soybeans.

Some have asked if there are other concerns to grazing these volunteer soybeans. Extension Forage Specialist Bruce Anderson notes: “Soybeans can cause bloat, but the incidence is low. The young green plants may be more risky. Founder would be a possible problem with a sudden diet change and too many unsprouted beans in the diet could cause excess fat; I think the maximum is about 3 lbs of beans per cow.” 

“I’d try to limit the amount of grazing for a few days, maybe feeding a very palatable supplement like a ground forage/distillers mix and reduce the amount of this supplement each day for a week or so. And keep a dry, palatable hay always available free choice.”

Related Nebraska Extension Resources

Also see

• Nebraska Extension NebGuide, Herbicide Options for Planting Forage Cover Crops Following Corn and Soybeans
• UNL BeefWatch article, Keys for Corn Stalk Grazing
• Corn Stalk Grazing Calculator, an Excel worksheet for matching livestock size and numbers with corn stalk acres needed
• Video: Extension Beef Specialist Rick Rasby discusses how cattle graze corn stalks and how to set an appropriate stocking rate.