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Extension > Local Extension Offices > Dakota > County Agriculture Educator > Articles > Intro to cover crops

Intro to cover crops

Soybeans in wheat and rye stubble, Le Center, MN

Cover crops are popping up in the news and in fields across Minnesota. This article is meant to be an introduction to the basics for those who feel overwhelmed and want somewhere to start.


What’s your goal?

A lot of options are available. Focusing on what you want to use cover crops to achieve will make which option is right for you much clearer. So why do cover crops appeal to you? Start with one or two goals that are most important to you:

GoalThe basicsLearn more
Reduce soil erosionSoil is vulnerable to erosion when not enough residue is left after harvest. Low residue is common after soybean, canning vegetables, and silage corn. A grass cover crop that produces a lot of high-carbon residue and fibrous roots can help hold soil.Managing Cover Crops Profitably:
Oats, pp. 93-97;
Rye pp. 98-105
Build soil organic matterGrass cover crops produce a lot of fibrous roots that build soil organic matter. That's why such beautiful dark soils built up under the prairie here in the Midwest. Oats, pp. 93-97;
Rye pp. 98-105
Break up compaction or increase infiltration"Tillage" radish produces a long taproot that decomposes quickly over the winter, leaving holes (macropores) in the soil. It doesn't leave much residue, so some like to pair it with an erosion-preventing grass.Brassicas and mustards,
pp. 81-90
Smother weedsWhen weed pressure builds up, one option is to draw down the soil weed seed bank by rotating into a mowing tolerant forage crop. If you don't have a market for forage, a "smother crop" can be planted for a full season or a shorter window. Additionally, in a prevented plant situation a cover crop can be planted to prevent erosion and compete with weeds.Overview of legume
cover crops, p 116;
Rye pp. 98-105;
Buckwheat, pp. 90-93
Catch nitrogen left at the end of the seasonGrasses are a good choice here, because their large root
systems explore a lot of soil area, and they do not produce their own nitrogen. Cover crops used to scavenge excess
nitrogen are sometimes called a "catch crop."
Oats, pp. 93-97; R
ye pp. 98-105
Produce nitrogen for next year's cropLegumes, like alfalfa and clover, grow root nodules that host nitrogen-fixing bacteria. Cover crops used to produce
nitrogen are sometimes called a "green manure."
Overview of legume
cover crops, p 116
Produce forage or another harvestable cropCover crops can be a valuable source of forage. If you produce livestock, this is the easiest way to derive revenue from a
cover crop. Biofuels, oilseeds, and other niche market crops are more cutting-edge possibilities.
Overview of legume
cover crops, p 116
Peas do double duty,
p 140

 

What’s your crop rotation?

Your crop rotation will determine how long the window is to plant and terminate a cover crop. A crop of sweet corn or peas is usually harvested early enough to leave a long window to grow a fall cover crop. Soybeans may be harvested early enough to plant a winter cover crop after harvest, but if you plan to plant corn the following year, the best option might be to plant a cover crop that winter-kills, so you won’t have to worry about terminating the cover crop before planting corn.

Not sure where to start? Here are two simple ways to try including cover crops in your rotation:

If your rotation is...Try this...Then in the spring...
Soybeans followed by cornPlant spring wheat into the first soybean field you harvest before Oct 20 (seeding rate 50 to 90 lbs/A).The spring wheat should winter-kill, allowing you to do your spring tillage and planting as usual.
Canning vegetables followed by cornPlant spring wheat between
vegetable harvest and Oct 20th (seeding rate 50 to 90 lbs/A).
The spring wheat should winter-kill, allowing you to do your spring tillage and planting as usual.

Learn more

 

How can we help?

If you want to have a one-on-one conversation about how cover crops might fit into your cropping system, there are three people here at the Dakota County Extension and Conservation Center would be happy to help you make a plan:

  • Neith Little, Dakota County Extension, 651_480_7723
  • Ashley Gallagher, Dakota County SWCD, 651_480_7781
  • Michele Wohlers, USDA-NRCS,  651_463_8665

 

Neith Little, Dakota County Extension
Reviewed by Scotty Wells, Jill Sackett, Ashley Gallagher

 

Posted 11/13/15

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