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Solving the alfalfa-grass equation

Solving the alfalfa-grass equation
Planting a mix of alfalfa and grasses has helped farmers grow quality forage.

By Jennifer Bradley

Alfalfa can be a tricky thing. Planting a mix of alfalfa and tall fescue, orchardgrass or meadow fescue grasses has helped farmers across Wisconsin provide quality forage, retain a quick recovery and also utilize a variable of maturity rates. It's a tactic many are using with success.

The right mix
Dan Undersander, University of Wisconsin Extension forage agronomist, says there are a number of reasons to plant an alfalfa-grass mix. First, it helps combat challenging soil types.

2014 was a good year to plant grasses with alfalfa because the weather was cooler.

"Some farmers plant alfalfa-grass mixes because they have a heavy soil with low spots where the alfalfa drowns out, and if they have grass, it's something which can still grow there," he says. Second, if a farmer is feeding a high percentage of corn silage in their ration, one issue is maintaining a low enough level of non-fibrous carbohydrates. Watching this closely prevents animals from contracting rumen acidosis.

"Alfalfa is often fed as a mix, but alfalfa has more NFC than grasses, so if we feed an alfalfa-grass mix, we're feeding a lower NFC forage," Undersander explains.

He says there can be issues with growing grass and alfalfa together, and would not recommend it unless one of these two situations exists where the need offsets the extra difficulty. The practice, however, is common in western Wisconsin, reaching to the Twin Cities of Minnesota.

In Wood and Clark counties, he says it's been standard practice for 50 years because of the wet soils and low soil spots. The area from Marshfield to Eau Claire also has farmers doing the same, because of soil drainage situations.

To mix alfalfa and grass for balancing the corn silage ratios is a newer concept, Undersander explains, and one that is being used more today and all over the state.

Challenges with grasses
Undersander says 2014 was a good year to plant grasses with alfalfa because the weather was cooler, but in 2013 the opposite was true. The challenge becomes picking a late maturing variety grass.

"Otherwise, on first cutting if it heads out, it will be low quality when the alfalfa is ready to cut," he explains.

The problem that brings is if a rainy period hits during first cutting, the grass is maturing faster than the alfalfa. If a farmer isn't able to get in the field, the grass may head out and Undersander wants farmers to remember it only does that once a year.

"The issue is first cutting," he says. "On the second, third and fourth cuttings it can actually widen the harvest window a bit, and that's a plus." 

Then the other challenge becomes grasses being more susceptible to dry weather and their yield will reduce more than an alfalfa yield if that is the situation. With these two challenges, he says variety is the solution.

 "Selecting the variety is more important than selecting the species," this agronomist says. Undersander offers three species (orchardgrass, tall and meadow fescue) which are good fits for alfalfa. "Because if you get the wrong one that has rust or early maturity, you're not going to be happy with the variety," he adds.

He says if a farmer instead chooses a late-maturing variety with rust resistance, it will yield a nice alfalfa grass mixture.  

The best advice he has to offer about the mix equation is to establish a stand that is approximately 30% to 40% grass (of the dry matter). Higher than that will be more affected by drought and second, deplete the alfalfa's nitrogen supply and subsequent yield reduction.

For those farmers mixing grass because of the corn silage NFC issue, Undersander says mixing 30% grass with alfalfa is a good idea.

 "For other farmers, going more 50-50 with their alfalfa/corn silage, then maybe it's not so important to have grass in there."

With two minuses but a number of pluses, Undersander says growing the alfalfa-grass combo is another tool in a farmer's box to be used when appropriate.

Bradley writes from Chilton.

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