Get cover crops ready for planting
What’s next for my cover crop?
Matt VanTilburg: It’s time to plan for a successful spring planting season. Several factors impact spring cover crop management decisions, including: termination method and timing, cash crop to be planted, cover crop species and, of course, weather.
How can I kill the cover crop?
VanTilburg: Cover crops can be terminated several different ways, such as tillage or roller crimping, herbicides, or naturally by weather through winterkill.
Why not just use winterkill?
VanTilburg: Only a few species will winter-kill. Oats, radishes and buckwheat will die with cold temperatures.
Cover crops that winter-kill do not require you to change spring management decisions as much as overwintering covers do. Oats and radishes are a good way to start in cover crops. They leave a field with some decaying residue by spring. Use a normal burndown, and no-till right into it.
What about tillage or crimping?
VanTilburg: I don’t recommend tillage or roller crimping to kill cover crops. Crimping is performed too close to cover crop maturity, and most farmers don’t want to wait that long to plant their cash crop. And cover crops should be used to replace tillage.
That leaves herbicides, which are the most common and effective way to terminate covers in the spring.
What about annual ryegrass?
VanTilburg: Annual ryegrass is probably the hardest cover crop to kill, although following a few tips can help control it successfully. I recommend these guidelines: 44 ounces of Roundup PowerMAX (or 64 ounces of generic 4LB), 15 gallons of water per acre, 17 pounds of AMS per acre (no liquid substitute), and 1 pint of LV4 2-4,D to control marestail. Use a flat fan nozzle, not air induction tips.
Do not use atrazine or a UAN carrier. Adding a residual in the spray tank will antagonize with the glyphosate.
When should I spray?
VanTilburg: With annual ryegrass, night temperatures need to be at least 50 degrees F, and the grass must be actively growing. It isn’t the first thing to green up in the spring. Winter temperatures will burn down annual ryegrass to the crown so it looks dead, but it’s not. If you spray it before it has started to regrow, the glyphosate will not work.
VanTilburg: Another spring concern is the carbon-to-nitrogen ratio of the cover crops. If the value exceeds 30-to-1 for C-to-N, then the nitrogen will be immobile. If this occurs, front-loading of N at corn planting will correct any issues. The immobile N will mineralize and become available later in the season, so the total N need will not increase with a cover. In fact, total N use should decrease over time with cover crops.
This article published in the March, 2015 edition of OHIO FARMER.
All rights reserved. Copyright Farm Progress Cos. 2015.