Why cover crops are worthwhile
Planting cover crops is like eating your vegetables – just because you know you should doesn’t mean you will. And like vegetables, the good news about cover crops is the same as the bad: they’re just too beneficial to pass up. While the last thing you probably want to do after an autumn harvest is plant a whole new crop straightaway, almost every part of your agricultural system will thank you.
With that in mind, the University of Vermont Extension is leading a weekly series to sell you on planting cover crops once and for all, and to give you the tools to do it right.
First in the series was a session focusing on their potential as forage. There are those who believe that cover crops should do nothing but facilitate rest for your soil, but cover crop expert Etienne Sutton isn’t one of them. As program director for the National Cover Crop Variety Testing Network, which fills a gap in cover crop trials and information dissemination, Sutton considers herself “a proponent of thoughtful consideration of cover crop as forage.” On top of nourishing and protecting the soil from erosion, cover crops can be game-changers for livestock, offering both grazing and stored feed.
For what amounts to a 12-month cropping system to succeed, the timing is pretty tight. This is especially true for the upper Northeast, where autumn temperatures can drop quite precipitously. So a corn harvest will have to be almost immediately followed by forage planting – such as winter rye, which Sutton uses as her primary example of a forage cover crop. Done too late, tillering sharply declines (tillers account for over half of the biomass of the yield), and the seeding rate will have to go way up. Proper tillering requires the seeds to be in the ground between four and six weeks before the temperatures freeze.
“A lot of planning has to go into that,” Sutton said. “It’s not just ‘throw in the cover crop whenever you have time in the fall.’”
If you manage to get the right crop in the ground at the right time, you can expect it to return your hard work and good timing with plenty of yield. If you’ve selected winter rye, this will be especially true, thanks to the hardiness of the crop.
“Really it can grow on cement,” Sutton said (only half-joking). In their study, they tested different species, and cereal rye took top prize for autumn establishment and spring stand, followed by hairy vetch and crimson clover, which both outperformed winter peas. The study also showed that cereal rye proved the most adaptive across regions.
Whatever the species or variety you select, don’t forget to fertilize. For livestock operations, an abundance of manure will naturally facilitate this task, but if necessary, synthetic fertilizer will also keep up the biomass for spring harvest. When you’re ready to harvest, don’t forget to account for the loss in nutrients when it comes time get the next crop in the ground.
As with autumn planting, the trickiest part of the spring harvest of your cover crops will be timing. The window is small, and it comes early. For storage feed, harvest needs to come at the boot stage. This moment doesn’t last long – it moves from boot to flag leaf very quickly. With such rapid growth, you really only have a few days on either side. It’s tricky, Sutton acknowledged, and while it’s always good to strive to harvest at the optimum moment, your best effort will be enough.
“As a farmer all that can be hard to manage,” said Sutton. “As soon as there’s a window in early spring, people are out mowing regardless of the stage. At that time of year everything is up in the air. If you get a window to harvest to take it.”
If you’re worried about timing, variety and species selection will really come into play. If, for example, you want your corn to go in the ground by mid-May, a small grain that heads out earlier is for you. Winter rye, for instance, comes in 10 days earlier than barley. Winter wheat, on the other hand, heads out later.
When it comes to feed, the stakes are high, so the harvesting process can be somewhat delicate. As Sutton cautioned, “The concern is ash content in feed, since you don’t want to be getting soil in the feed. Once it’s contaminated with soil it reduces the quality and can risk animal health. You need to keep the mower high.” Her recommendation is to keep it four inches or higher, and to avoid raking the soil.
After harvesting, the other crucial element is making sure the forage has completely dried before storing it – admittedly difficult when the weather is in its springtime flux. “Use an inoculant when harvesting is critical here, and make sure it gets packed properly,” she advised. “A lot of these crops have hollow stems, so reducing the chop length helps. Even with high quality feed it can turn into a bit of a mess.”
If all that sounds too intimidating, there is the pasturing option. Livestock would be happy to do their own harvesting for as long as you let them. “Cover crops are great for pasture. There are a ton of benefits to the farm – you get the cows outside earlier and they’re grazing with high quality, high biomass feed,” she said.
In their test studies, they’ve been able to graze the cover crop twice before moving cows to their regular pastures. “This provides a wonderful opportunity for farms if they can work it into their cropping system,” said Sutton.
The successful execution of cover crops as forage is no mean feat. It requires careful selection, tight timing and fastidious harvesting. But the hard part is front-loaded. Once you’ve made the right plan for the particular needs of your farm, the cover crops will immediately give back. You’ll wonder how you, your soil and your livestock friends ever went without.
by Holly Devon
