Grazing Cover Crop Considerations

Blog Post

With a growing number of cover crop acres across the state of Iowa, some producers are looking to cover crops to help extend their grazing season. While cover crops have the potential to be an extra forage source and reduce feed costs, there are challenges with using cover crops as a forage source. This ICM Blog shares some best management practices complied from a survey of producers who have prior experiences with grazing cover crops along with what we’ve learned in our grazing cover crop studies to help you get the most out of grazing cover crops.

Be flexible when integrating grazing cover crops into a row crop operation. This is especially true this year with a late harvest. Normally oats and brassicas are recommended for fall grazing because they produce more forage in the fall. However, this year with a later harvest and later planting date for the cover crop, an overwintering cereal grain is probably the best recommendation. Even if there is a short growing season this fall, it will still produce forage growth next spring for grazing or harvest.
Double check pesticide labels, especially herbicide labels, to make sure it is legal to graze the cover crop. Check crop rotation restrictions as well as grazing restrictions. A good source to look up pesticide labels is http://www.cdms.net/Label-Database. Also, check out the ISU Extension and Outreach publication Crop 3082 “Herbicide use may restrict grazing options for cover crops” .
Cows or pairs can usually get by with less fencing, but good, reliable fences are needed if grazing feeder calves that may have less respect for fences and are new to a field. Water access is also important as we consider grazing in the winter months.
Use the pluck test to determine when the cover crop is ready to be grazed (i.e. pull on the plant and if it doesn’t pull out of the ground, it is ready to be grazed).
If possible, pull livestock off when conditions become wet to avoid compaction issues or have a sacrifice area for the livestock. This is especially important when spring grazing.
Several cooperators suggested the need to supplement lush cover crops with a dry forage source. Recent research would suggest supplementation is beneficial when the quantity of forage growth may not meet the needs of the cow, or when the energy density of the lush growth may not be adequate based on the number of bites a cow can consume in a day. More research in this area is needed to determine actual needs, but in short growing years such as this fall, pregnant cows will probably benefit from additional feed supplementation when grazing cover crops.
Nitrate and sulfur toxicity are some animal health concerns that can be associated with cover crops. Read more on these animal health concerns in this ISU Extension and Outreach publication IBC 129 “Managing Cattle Health Issues When Grazing Cover Crops.”
If using an overwinter cover crop, it is recommended to use a herbicide to terminate in the spring. If grazing in the spring, wait a few days after pulling the livestock off to allow the cover crop to grow back some before terminating with a herbicide.
Start small and don’t give up if the first year it doesn’t work well. Some years Mother Nature just doesn’t give us enough growing days to provide for grazing of cover crops; however, there are still other benefits to cover crops.