A cover crop is a very basic thing that most farmers and home gardeners know about; however, cover crops remain underused.
For those new to growing crops, including home gardens, a cover crop is a planting put out following a harvested crop. This is usually done in the fall so there is a plant covering on the ground instead of bare soil.
Cover crops protect our soil from erosion, many help provide some weed control and can give us another crop that we can use, depending on what we sow as our cover crop.
The soil erosion protection speaks for itself. The weed control can vary by which crop we choose and what weeds we are battling, but all help some.
Some cover crops are a source to get more organic matter into the soil, just turn the cover crop into the ground in the early spring of the following year before planting. This can help with drainage, root growth of future crops or just the texture of the soil.
For some, this can mean an additional crop they can harvest in the spring, such as a small grain like wheat or oats. It can be used for early season grazing, it can be cut and made into haylage or it can simply be harvested for the grain to be feed later or sold.
Others may see a cover crop as a way to extend the fall/winter grazing season.
Many think cover crops are only for fields, large or small, that have had crops grown on and removed from them, like corn or bean fields. This is not necessarily true. We also can put cover crops into overused pastures or hayfields or ones that need help during the colder season.
Let’s start with crop fields and gardens. When a field has been harvested or a garden is finished for the year, it is cover crop time. Many times, we choose to go with a small grain as our cover crop, the main ones being wheat, rye, oats and barley, with wheat by far the most common. But use the one you can find seed for in the quantity you need.
An advantage to using small grains as a cover crop as opposed to a grain crop is you do not have to use certified seed to try to maximize yield. You can use common seed, or bin run, which means it may be a mix of varieties, or the variety may be unknown, and that there is no guarantee on quality, being weed free or germination rates. However, it will be quite a bit less expensive.
Wheat is the favorite choice, mainly because seed can be easily found, it is relatively inexpensive and it is sort of the traditional choice. It is also probably easier to manage and more versatile than some of the others.
Rye may be the overall best small grain cover crop. It is good at suppressing weeds, restarts growth early in the spring, and has extremely winter hardy varieties to choose from. But it may be a challenge to find seed.
Oats do not produce as much growth as the other options. If using oats, you must be sure to use a winter variety, not a spring variety, or you will be very disappointed.
Barley can definitely be used, but it can be more susceptible to winter-kill, and is very susceptible to yellow dwarf mosaic virus, a disease that can really damage the stand.
If using a small grain, see the chart following for timing, seeding dates, etc.
You can use either an annual or perennial grass as a cover crop.
I recommend ryegrass, which suppresses weeds and, if planted early, can get good top growth before cold winter weather hits. It may winter kill in some very cold years. But it can be grazed, or even cut for hay early the next spring. If not cut before going to seed, it can re-establish itself the following fall, but will die back naturally as the temperature starts to rise in late spring.
A couple of perennial options are perennial ryegrass and fescue. The issue with both of these is that they have to be killed the next spring, or they will continue to grow for possibly years.
Another option is to use legumes. As many know, legumes are plants that take nitrogen out of the air and use it themselves or "fix" it on their roots as small nodules, which other plants can use.
There are several options when considering legumes as a cover crop, but truthfully, there is only one that I have ever recommended, and that is crimson clover. Other options are hairy vetch, bigflower vetch and Austrian Winter Pea.
I recommend crimson clover because you can find seed for it around here in stock, usually. The other three can be harder to find seed for. But if you do want to use one of them, you can always special order the seed in advance.
The vetches can readily grow in our area, and it is very common to see hairy vetch as a volunteer plant in many of our hayfields and pastures. And that can be one of the problems with using these as cover crops.
If not killed or turned under before going to seed, volunteer plants can be a real problem for several years going forward. If choosing vetch to use, go with the hairy vetch, as it will fix more nitrogen and have more total growth. And it matures later, so you have a little more time to turn it under before it goes to seed.
The Austrian Winter Pea can make a very good cover crop, but you must choose Canadian varieties to avoid excessive winter kill. And if using on land that could be highly erodible, you need to plant it with a small grain. Again, it needs to be killed or turned under before going to seed.
Crimson clover is an annual, so is less likely to be a volunteer weed problem going forward. It is subject to winter kill, but many have grown it successfully for years and had minimal problems with it.
If you want to maximize growth and yield, planting a mixture is the way to go. Any of the legumes can be seeded with a small grain. If doing this, reduce both seeding rates by half. I recommend crimson clover with wheat. Both seeds are easily found locally and they just work well around here.
If you want to read more details about these cover crops, put this link in your browser line and it will take you to ID-113, Winter Cover Crops for Kentucky Gardens and Fields, a UK Extension publication: www2.ca.uky.edu/agcomm/pubs/id/id113/id113.pdf
And as always, if you have any questions, give us a call here at the Boyd County Extension Office at (606) 739-5184.
LYNDALL HARNED is Boyd County Extension agent for agriculture/natural resources.