Nebraskaland

June 2024 • Nebraskaland 41 Our present renters, two young cattlemen, graze the pasture with 30 cow/calf pairs from about April 15 to June 1. This is a heavy stocking rate and the pasture is often golf-course short when the cattle are taken off , but hard grazing is needed to stress the stubborn brome and bluegrass. At fi rst, the renters were hesitant to turn their cattle out in mid-April, fearing there wasn't enough grass to sustain them. I maintained that the young, tender growth of brome and bluegrass is packed with nutrients and would put pounds on their animals. They consented, and when the animals came off the pasture that fi rst year, one of them sheepishly admitted, "Our calves sure look good." Many native plants, including milkweeds, ramp up their growth in early June and, if left in the pasture, the cattle will forgo the brome and bluegrass and eat the nutritious, early growth of these plants, setting them back as well. We begin fall grazing about Sept. 15 and usually take the cattle off the pasture sometime in November. Cool fall temperatures trigger brome and bluegrass to resume growth after summer dormancy. At this time of year, the sugars they produce through photosynthesis are stored in their roots and used for the next spring's growth. Hard fall grazing removes the leaves, stifl ing photosynthesis, food storage and the plants' future vigor. Ranchers with multiple pastures dominated by non-native grasses and nowhere else to graze their livestock can select their most wildfl ower- rich pasture for intense spring and fall grazing while grazing their less- diverse pastures during the summer. Occasionally, they can summer graze the diverse pastures, burn them or rest them the entire growing season. Doing so will benefi t wildfl owers, milkweeds and monarchs in at least one of the pastures. Herbicide and Seeding Although it sounds contradictory, Grace and I also use herbicides to promote milkweeds. In fall, we search the pasture for the dried, dormant stems of common and whorled milkweed and spray glyphosate herbicide (its many brand names include Roundup) on the still-green brome and bluegrass surrounding the stems. Glyphosate is a contact herbicide that kills only actively growing plants — it does not remain active in the soil. The following summer, reduced competition from the non-native grasses allows milkweed plants to sprout new stems, often forming dense colonies. We spray glyphosate only after at least two hard freezes, where nighttime temperatures drop to at least 28 degrees Fahrenheit. The cold further stimulates the non- native grasses to move nutrients from their leaves to their roots for winter storage, and the herbicide is carried along for the ride. Once in the roots, the herbicide is more eff ective, killing the entire plant. We spray only when daytime temperatures reach 50 degrees or higher for two consecutive days, spraying on the fi rst day at a rate of two quarts per acre along with a non-ionic surfactant and ammonium sulfate. We have had our best luck killing brome and bluegrass by spraying in late November, but spraying into December can also be highly eff ective. Using a boom sprayer mounted on an all-terrain vehicle, we also treat larger areas of brome and bluegrass, up to about a quarter acre, in the fall, and then hand-sow milkweed and other wildfl ower seed in late fall or early winter. We only seed in years when the prairie has been grazed or burned and has little thatch, as this ensures good seed-to-soil contact and germination. Using this method, about 50 butterfl y milkweed plants with glorious orange blooms now adorn our prairie, while a few colonies of Sullivant's and swamp milkweed grow in moist soil near an In spring, cattle relish grazing the nutritious early growth of smooth brome and Kentucky bluegrass, and often shun grazing wildfl owers.

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