Anyone who has kept up with us at Merit or Myth knows that there is a growing list of benefits that are associated with cover crops. From reducing runoff and erosion to increasing organic matter and suppressing weed emergence, it seems more research comes out every year proving the merit of this practice.
As with all tools, however, cover crops are only one piece of the puzzle, not the whole picture. This is because the fields in which we grow our crops are all dynamic ecosystems that are influenced by everything with which they come in contact. Given that we’re in the middle of a three-part series on weeds, it’s important to understand how the implementation of cover crops effects weed management, specifically when it comes to herbicide usage.
THE INTERSECTION OF HERBICIDES AND COVER CROPS
For better or for worse, the practice of spraying herbicide has conventionally been an accepted reality of farming. It makes sense: in simplest terms, a producer looking to grow plant A is going to encounter some problems when mother nature wants him to grow plants B, C, and D along with it. The quickest way to subdue mother nature? Spray chemicals, ask questions later.
We’ll leave the long-term effects of spraying herbicide for another time (if you would like a bit more information on this, check out our own Dr. Buz Kloot’s take in his video, “Weeds: A Chemical or An Ecological Problem?”). The bottom line for now is that, regardless of what it does to the environment in the long-term, when it comes to herbicide, very few of us have a thorough grasp on the subject. Extension agent at the University of Wisconsin Dan Smith has seen this firsthand when it comes to the crossroads of herbicide and cover crops. His advice? Make sure you read the label.
“Most herbicide labels contain information for forage crops,” Smith says, “but they don’t contain information for cover crops. It’s important to dig into that label to make sure you don’t have any restrictions on that herbicide, things that would prevent you from legally feeding that to your livestock or selling it to a livestock farm.”
Easier said than done, we know. Reading herbicide labels isn’t exactly like flipping through your favorite Dr. Seuss book. These labels are routinely long and include terms and chemicals of which not every farmer holds a comprehensive knowledge. However, it’s more important than ever for us to understand what these labels have to say.
HERBICIDE: TIMING IS EVERYTHING
While the benefits of cover crops are extensive they don’t exactly happen overnight. This reality has lead farmers to seek more readily available ways to utilize cover crops in the short-term, such as using them as a forage crop. We must be aware, though, if we’re to use cover crops as forage that some herbicides carry significant risk for animal consumption. In this regard, timing is everything. This is why Smith says that a good place to start when it comes to reading herbicide labels is the rotational crop section.
“The rotation data is a legal requirement from the time of herbicide application to the time that we’re going to harvest or graze that cover crop that turns into a forage crop,” Smith says. “That could be a diet for cover crop establishment, but remember that you can grow a cover crop following any herbicide application as long as you never harvest that cover crop.”
Of course, individual herbicide types and brands have extensive variation and herbicide carryover can be effected by a variety of conditions, from organic matter content to soil pH to rainfall and soil type. This is yet more evidence that the greatest teacher when it comes to farming is below our feet. Read your herbicide labels and find out how they affect your soil firsthand. It may be a little more work in the short-term, but once the benefits of cover crops are realized, you’ll be thankful that you did.
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