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Grazing sheep in alfalfa for weed control

Progressive Forage Associate Editor Carrie Veselka Published on 05 October 2017
sheep grazing alfalfa

For alfalfa producers, mild winters come at a price. Thanks to hot summers and mild winters, alfalfa growers in California’s Central Valley can usually depend on six cuttings of hay each year, but since they do not experience a true winter, weed infestation in their dormant alfalfa stands can be a problem.

Mick Canevari, a farm adviser emeritus with the University of California’s San Joaquin county extension, says that winter weed stands in alfalfa fields can reach up to 2 feet tall. One solution to the weed problem is, of course, applying an herbicide, but some producers use a weed management system dating back to the farmers who settled the valley several generations before: sheep.

Sheep and other small ruminants are a great resource to Central Valley alfalfa growers. Sheep can graze alfalfa without bloating like cattle and horses do, and thoroughly graze through weeds and old stems to leave a clean field behind them. “It is and it has been for decades a very effective way to minimize weeds in forage production,” Canevari says.

Sheep are usually turned out from October to February, when the alfalfa has entered its dormancy. Canevari says the dormant period is the most vulnerable time for alfalfa. “These winter weeds are adapted to that time of year and, essentially, can swallow up the alfalfa because it’s not competitive right then,” he says.

Mowing machines

The most visible and positive aspect of what grazing sheep do for a producer is grazing off winter weeds. “We have a lot of broadleaf weeds and grasses that grow in the wintertime that are very non-desirable for alfalfa, and these sheep will just come in and mow them down,” Canevari says. “Our weeds in the wintertime can be 2 feet tall out in the field, and when the sheep get done eating through a field, the weeds are probably 2 to 4 inches tall, so they take off 90-plus percent of the vegetation out of the field, which is fantastic.”

Dynamic duo

Grazing a weed down to the ground doesn’t actually kill the plant, so sheep cannot be the sole solution to winter weed problems. The weeds are still alive and will most likely have time to grow back a little before first cutting, but reducing them to stubble is a great opportunity for producers. After the sheep come through and pick the field clean, the producer can apply herbicides that will have greater contact with the weeds and be much more effective. Nicholas Mussi, who grows 1,500 acres of alfalfa in San Joaquin County, says this is his main reason for allowing sheep on his fields in the winter.

“It’s not only for the weeds that they eat, it’s for the herbicides that you’re going to put down,” he says. “If you have a standing crop of alfalfa, you don’t get the ground contact with the pre-emergence herbicide. We do it to clean off the ground so that we get better coverage with the pre-emergence.”

Canevari says this makes it possible for producers to not only hit the targeted plants easier, making the herbicide more effective, but allows them to use lesser amounts as well. “You pretty much clean it up and spray it so that the first cutting looks good,” Mussi says. “If you spray it with the big weeds there, then you have all of those plants in your first cutting the next year.”

Alfalfa stems

Another benefit to sheep grazing dormant alfalfa is the reduction of old alfalfa stems. Whether the last crop is taken for hay or alfalfa haylage, the old stems that remain in the field can lessen the quality of next year’s first crop. Without some sort of cleanup involved, old stems, weed carcasses and other bits of flotsam end up in the first crop, which can be problematic in a market that runs on quality. “If you have sheep, they go in and do a wonderful job of cleaning up that old alfalfa that’s there in the winter that’s not growing anymore and they get rid of the stems and rid you of all the diseases that are on those stems and hitchhike into the next season,” Canevari says.

Grazing sheep also reduce the amount of weevils transferred in hay. “A lot of people don’t realize this, but in California, the alfalfa weevil female comes into the field around December and deposits her eggs into the stems of existing alfalfa, and by February, the larvae are hatching, and we always have to spray again to catch the weevil,” Canevari says. “But the sheep, by eating the stems, minimize the amount of weevils that hatch in the spring, because they are eating a lot of the eggs and a lot of the adult weevils that are in the fields, so we also benefit from a little insect management from sheep.”

Benefits for everyone

Canevari says that only 10 to 20 percent of the alfalfa fields in the Central Valley are grazed with sheep in the winter, which is a missed opportunity on both sides. “It’s a plus all the way around.” The sheep operators pay a small amount of money for their sheep to have good grazing, and the alfalfa growers are happy to have them come in and clean up to help them kick-start their next growing season. “I call it a good, old symbiotic relationship between a sheep farmer and an alfalfa grower,” Canevari says. “There’s a lot of good on both sides that they benefit from.”

John Cubiburu runs over 4,000 sheep in the San Joaquin Valley and grazes alfalfa fields for roughly 15 to 20 producers in the San Joaquin Valley and surrounding area each year. He sees sheep grazing alfalfa fields as both a great source of forage for his sheep, but also a service to the producer, and uses that approach when working with the farmers. “With the right attitude and approach, most farmers out there that use sheep for the first time tend to continue to use sheep because they recognize the value that the animals provide to their land, particularly the alfalfa,” he says.

He says the stocking rate and time it takes to graze down a field changes depending on the time of season the sheep graze and the volume and nutritional value of the vegetation in the fields. He says that after the winter frost and rains start, the sheep move through the fields at triple the rate that they would in October.

Cubiburu says that the lambing schedule in California is arranged to benefit from the winter grazing that is available. “Alfalfa is by far the superior feed for raising a lamb, so in California we traditionally have targeted our lambing season to when we have access to the alfalfa fields, generally in the same time that farmers are no longer cutting to make hay. California’s sheep industry has evolved to meet those time frames.”

Cubiburu says the most important factor in his business is relationships. “Every ranch, every family operation, every farmer is going to be different, and the secret to making this all work is a partnership and an understanding of time frames – when the farmer wants you to come in, when he wants you to come out, the goals and objectives of what he’s trying to accomplish and making sure that works with your operation,” he says. “It’s not always about money if you’re delivering the service and value in the end.”  end mark

Carrie Veselka
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PHOTO: California’s Central Valley produces 70 percent of the state’s yearly alfalfa hay crop, according to the University of California Alfalfa Workgroup. Photo courtesy of Thinkstock.