How Growers Can Produce Forage Full Time Without Row Crops
When alfalfa begins to thin and rotating to corn or beans isn’t an option, add grass to the mix.
By Jason Jenkins | Photos By Rachael Long
It’s a predicament many small-acreage forage producers find themselves in regularly: When pure alfalfa stands naturally begin to thin, how can field productivity be maintained for continuous production of hay?
“This is a very common issue,” says Dennis Hancock, Extension forage specialist at the University of Georgia. “While alfalfa provides high-quality forage, it also produces chemical compounds that enter the soil and essentially prevent new alfalfa plants from establishing.”
To overcome the effects of this process, known as alfalfa autotoxicity, producers often will rotate an alfalfa field to another crop such as corn. When there aren’t row or other crops in the mix, growers still have options, but reseeding alfalfa immediately isn’t among them. Forage experts recommend that producers generally wait no fewer than eight months, and usually longer, before attempting to grow alfalfa again. Otherwise, the autotoxic effect will likely curtail establishment of the new stand.
“It’s a bit soil and rainfall dependent. You’re really pushing the envelope if you try and go back in with alfalfa in the fall after terminating in the spring,” Hancock says. “Most of the time, we would wait until the following spring or fall to reseed alfalfa. So, for many producers, it’s an opportunity to interseed some grass to carry that alfalfa stand for another couple years.”
Using the Right Variety of Grass
In order to continue growing forage in a field while avoiding the effects of autotoxicity, Hancock says producers can interseed alfalfa stands with a cool-season grass. Deciding when it’s time to add grass should be based on the density of the alfalfa.
“There’s a significant yield penalty from trying to stretch out an alfalfa stand too long,” he explains. “Every stem below 55 stems per square foot is going to reduce the yield potential by 1.5 to 2%. If you’re at 45 stems per square foot, it’s time to do something. Alfalfa is too expensive to maintain to get anything less than 80%.”
Cool-season grasses such as orchardgrass and tall fescue are suitable complements to alfalfa in most regions, and Hancock says there are two considerations growers should keep in mind when managing a mixed stand. The first is weed control.
“Once we put a grass with a legume, that complicates our weed management program,” he says. “A lot of producers are growing Roundup Ready alfalfa, but once we add orchardgrass, for instance, it’s not Roundup Ready, so there are very limited weed-control options going forward.”
The second consideration when interseeding a cool-season grass is choosing a variety with the correct maturity. Hancock says a grower should try to match up the maturity of the grass with the timing of the alfalfa cutting. Growers may select early-maturing varieties or late-maturing varieties, depending on what their particular hay market desires.
“There are so many combinations, but the key is finding the grass that matches your needs,” Hancock says. “For example, many horse hay markets prefer a little bit of seed head present in an alfalfa/orchardgrass hay so that they know it’s orchardgrass. In that situation, a grower might choose an earlier maturing variety.”
Orchardgrass can be interseeded with a no-till or conventional drill; broadcast seeding also will work. The University of Wisconsin recommends a seeding rate of 5 to 10 pounds per acre, with the higher rate used when broadcast seeding. Hancock says fertilization should continue to be based on the needs of the alfalfa.
Similar considerations with variety selection, seeding and fertilization also apply to tall fescue. “Fescue with alfalfa is a great mix, and tonnage wise, it produces quite well,” Hancock says. “Now, if it’s going into the horse hay market, oftentimes there is a bias against fescue because of issues with fescue toxicosis. Regardless, a grower should consider an endophyte-free or novel endophyte tall fescue variety.”
In addition to extending the life of an alfalfa stand, mixing in grass also reduces the risk of pest problems. “Alfalfa weevil is much less of an issue in grass-alfalfa mixtures,” Hancock adds. “Potato leafhopper is also put off by having some grass in the mix.”
Going All Grass
After two to three years, a mixed alfalfa/grass stand will decline in productivity as the grass now starts to thin. At this point, Hancock says it’s time for a grower to begin the process of rotating the field to all grass in preparation for going back in with alfalfa once autotoxicity is no longer an issue. The forage specialist recommends growers consider planting a warm-season annual grass, such as teff in northern growing regions, or pearl millet or sorghum-sudangrass farther to the south.
“If you’re far enough south, producers might also incorporate a winter annual and get another crop,” Hancock says. “Typically, we would grow annual ryegrass. It’s straight up rocket fuel as far as forage quality.”
Also, Hancock encourages all producers to keep good records of all herbicide use. “Many of these herbicides have a very long residual, so it’s important to pay good attention to know how quickly you can come back and establish your alfalfa. You don’t want to paint yourself into a corner.”
For more advice on seeding into an existing alfalfa stand, download these guides from the University of Wisconsin (https://fyi.extension.wisc.edu/forage/files/2014/01/Thickening-Alfalfa-StandsFOF.pdf) and the University of California, Davis (https://alfalfa.ucdavis.edu/+symposium/proceedings/2003/03-227.pdf).