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Fine-tune your cover crop plans

Cover crops are pretty hot right now. And with the recent recommendation that mechanical tillage may not be the best idea this fall because of dry conditions in much of the Corn Belt, planting cover crops has emerged as a potential solution to the problem of keeping your soil well-conditioned between now and next spring.

"My fall tillage plan never seems to go as planned. I'll try to plant more cover crops -- rye grass and cereal rye, this year," says Crop Talk senior contributor buckfarmer. "Most of my ground is highly erodible, so I never do primary fall tillage anyway. I do like to lightly disk cornstalks, but it's a low priority."

If you're new to cover crops, though, the sheer volume of different options to plant may appear to be a major obstacle when you look specifically at your acres. So, what will work on your farm?

It starts with a close look at your acres, what you most need to accomplish with a cover crop, and the window open to you for getting it planted, says Pennsylvania State University Extension agronomist Jeffrey Graybill.

"Know what your goals are and what your planting constraints (timeliness, etc.) are. Cereal rye is the king of winter cover crops for a very good reason. It often meets multiple needs, takes abuse well, and is economical. Before switching to something different, know what advantages and pitfalls you may encounter," he says. "After mid-September, forget about growing a fall forage (oats) and focus on what your needs will be for the spring. Legumes tend not to grow as aggressively as grasses. After September 15, consider seeding crimson clover and hairy vetch with a companion, as part of a mix -- or not at all in October."

Then, layer on top of your time constraints what you need out of what you plant. When you will first need the crop's covering over the soil will be a major factor in nailing down what you plant, according to a report from Purdue University agronomists J.V. Mannering, D.R. Griffith, and K.D. Johnson.

"Cereals like rye or wheat are the most popular cover crops in Indiana for a number of reasons. They are easy to establish and fast growing; seed is readily available and relatively inexpensive. Legumes, on the other hand, do not provide cover as rapidly, but they do supply some nitrogen that can be used by a spring-seeded corn crop," according to the report. "Be sure to select a cover crop type and variety that is adapted to your section of the state. Hairy vetch, for instance, is better adapted in the southern part of Indiana because of its slow, early growth. In selecting a wheat variety, Hessian fly resistance and growth potential should be taken into account. Weigh the relative importance of the above factors in choosing the right cover."

For a lot of farmers, the right mix of cover crops is typically a product of a lot of experimentation based on the wide range of weather conditions they may face from year to year.

"Lots of trial and lots of error. When I was a kid, we raised tobacco and copped all our corn for silage. We always had a cover on that ground, since both crops left the ground totally bare," says Crop Talk's buckfarmer. "But even back then, it was kind of a system of whatever was cheap and easy. Usually it was wheat or cereal rye. Now use some radishes, turnips, oats if I get it planted early enough. Annual rye grass is probably my most used cover, but I'm open to about anything."

Take into account when you'll be planting those cover crops and when you'll be reaping their benefits. Crop Talk veteran adviser Shaggy98 has been planting his covers in the spring for their soil conditioning properties leading up to winter wheat planting in the fall. Though he didn't see ideal conditions in the last year and he's still tweaking his cover crop strategy, he says he's seen major benefits this fall.

"I tried a blend of tillage radish, forage peas, and oats this past spring, but the late freezes put a stop to them before they got a good start," Shaggy98 says. "However, when I no-till drilled that particular field to winter wheat this past week, that ground was so much more mellow then the rest of my ground it was unbelievable. Almost like driving across a sponge, so maybe I received more benefits than I actually thought I did. I'm considering the same blend next spring, but instead of drilling in late March, I will push that back to late April."

Management and economics

Once you select the right cover crop mix based on when you'll plant it and when you expect benefits from that crop, there's the task of getting that seed into the ground. And, you have just about as many options here as you do with the crop mix you select. It all depends on what you plant, too, according to Purdue's Mannering, Griffith, and Johnson.

If you're planting a small grain cover, it takes a different approach than if you're opting for a more legume-heavy mix.

"There are two recommended methods for seeding a winter rye or wheat cover crop: Into standing corn or soybeans in late summer (late August), broadcast the seed with an airplane or helicopter at a rate of 2 to 3 bushels per acre; or, after corn or soybean harvest, disk lightly, fertilize (if needed), and broadcast or drill the seed at a rate of 1.5 bushels per acre," according to the Purdue report. "After beans, the disking step could be eliminated if heavy-duty drills are used."

Aerial seeding is gaining in popularity because of its efficiency and cost. But make sure you account for the risks -- and there are more with this strategy.

"Aerial seeding is less work but more risky than drilling, because stands are highly dependent on late-summer rainfall," according to the Purdue report. "If corn is to follow corn, planting a medium- or short-season hybrid that can be harvested earlier will allow the cover crop to get better established before winter; this is a more important consideration in the northern half of the state."

Adds Crop Talk senior contributor tree fmr: "Have had cover crops flown on but never seem to get an even stand that way."

On the other hand, a legume-based cover crop mix works better when drilled or broadcast. "Aerial seeding of a legume on untilled land is just too risky in too many years. Also, legume seed should be inoculated before seeding with the proper species of rhizobia bacteria for N-fixation," the Purdue agronomists say.

What's this all cost? Finding that answer means breaking down each step in the cropping process. There's disking, seeding (drilling, broadcast, or aerial), seed, and fertilizer costs. Based on Purdue agronomy data, sowing a cover mix of rye, hairy vetch, and paraquat would cost anywhere between $32 and $40 per acre. Then, in this example, factor in the value of the nitrogen that your soil will gain.

"Even ignoring the N add-back, a cover crop usually more than pays for itself in increased production of the row crop that follows," according to the Purdue report. "Research studies usually show at least a 10% increase in yield when switching to well-managed no-till sod planting on drouthy or erosive soils."

What's your cover crop strategy? Add your comment below or join the discussion here!

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