WASHINGTON, July 8, 2015 –In years ahead, expect to see more beef cattle, dairy and sheep operators planting cold-tolerant forage crops in the summer to ensure leafy, nutritious plants in pastures for autumn to winter grazing.
With the U.S. trending to grass-fed and free-range livestock, organic farming and the expanded use of cover crops to protect and enrich the soil year-round, some farmers and ranchers coast to coast are adding brassicas – a group of plants such as turnips, tillage radishes, swedes (rutabagas), forage rape and kale – to late-season grazing.
Forage experts endorse the practice, pointing to the copious nutrition the brassicas deliver. Penn State University forage specialist Marvin Hall, says that in Pennsylvania they produce 3.1 tons per acre of dry matter, on average, at 90 days of growth. That roughly equals the U.S. average for a full year of alfalfa growth. Plus 80 percent to 95 percent of brassicas are digestible (versus 70 percent for high quality alfalfa), and they retain those high utilization rates when mature, remaining highly nutritious in whatever season they are grazed. Hall says, for example, that the typical seasonal stocking rate on a thriving brassica crop in Pennsylvania is about 160 cow (or 1,500 ewe) grazing days per acre.
Animal nutrition, however, can be a secondary purpose. Brassicas are often planted foremost as cover crops to increase soil organic matter, add surface residue to reduce erosion and provide habitat for beneficial insects. Also, brassicas are broad-leafed and grow low to the ground, providing a canopy that smothers weeds.
Researchers and farmers are trying brassicas in a bevy of ways, most often summer-seeding them in a blend with other grasses and/or legumes that will also flourish in cool fall temperatures. At USDA’s research station in Mandan, North Dakota, David Archer’s team has been double cropping some plots for six years: harvesting a crop of field peas, then quickly planting a mix of fall forage crops -- purple-top turnips, triticale, lentils, field peas, sunflowers and more – by the end of August so the crop will be ready for grazing cows in October.
The plants “grow well late in the season,” Archer says. “They tolerate the frost.” In fact, he has found that the first frost prompts turnips to start concentrating sugar in the root bulbs, and Archer says that is when the cows, instead of eating just the turnip tops, tend to start pulling the turnips out and eating them.”
Colorado State University researchers are trying something similar. They’ll interseed forage rape, turnips, tillage radishes and a hybrid Chinese cabbage into a field when corn is already about knee-high, says forage scientist Joe Brummer.
“The forage crop just sort of sets on the ground until the corn starts to dry down, and then the forage crops start to grow. Once you've harvested the corn, then you've got high quality, cool-season brassicas, rye grass, and those sorts of things that [the cattle] will eat along with the corn stover.” The forage crop mix “did really well for us last year. Think of it as a protein supplement for the corn stocks,” Archer says.
In his region, the plantings for fall grazing are done mostly in mid- to late summer, to stockpile forage in fields for mid-October to December grazing. “The idea is a forage for when grazing animals are coming off summer grasses, something to extend the grazing period to save input costs and feeding hay and that kind of thing.”
“Out here in the West, where it's drier and water is your limiting factor,” Brummer says, “you want an economic return on that cover crop . . . getting both the improved soil health plus a return by grazing cattle or sheep or whatever.” He expects that growing such “cocktails” of fall forage “is going to become more common.”
Last summer, in fact, northeast Colorado farmer John Heermann seeded tillage radishes with sorghum, sunflowers and a host of legume and grain crops into 160 acres with an eye to autumn grazing. He had cover crops on 700 acres to improve and protect the soil and wanted to experiment with renting out some of the acreage for fall grazing.
So he rented 160 acres to graze 100 cows for two months, rotating them every few days into new five- to 10-acre areas. He found the plants flourished, producing about 3.5 tons of dry matter per acre until hit by an unusual early-November blast of sub-zero weather. The radishes, sunflowers, sorghum, barley and oats did best in the late going, he says. This year, he’s adding white clover to his cocktail, plus another brassica – an African cabbage that’s similar to Brussels sprout.
· In the WEST, click here for a management report from Colorado State University.
· Click here for an overview on brassica usage in the MIDWEST from a University of Wisconsin agronomist.
· Back EAST, click here for tips from a Penn State University expert.
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