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> MSU News
Sheep turn into weed eaters for fallow field experiments
August 10, 2007 -- By Evelyn Boswell, MSU News Service
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Erin Snyder looks inside her hoop for plant remnants. If she finds any, she places the samples inside brown lunch bags for later examination. (MSU photo by Kelly Gorham). | |
BOZEMAN -- Erin Snyder really isn't playing an old children's game when she tosses a metal hoop into the air and watches it roll, slow and topple over.
The Montana State University senior is throwing the hoop across a field so she knows where to collect weeds left behind by 14 Rambouillet sheep. The animals have just spent 48 hours eating almost every weed, blade of grass and stray wheat plant on a fallow wheat field east of Bozeman. Their time up, Snyder shooed the sheep back to greener pastures and returned to the experimental plot to see how well they'd done.
"The sheep definitely did a good job. There's really nothing left," Snyder said as she crisscrossed stubble, dirt and sheep dung to inspect the area beneath her hoop. The few leftovers ended up in a brown lunch bag for later examination. The hoop flew nine more times.
MSU researchers Pat Hatfield and Hayes Goosey said weeds remove valuable moisture and nutrients from fields that are resting after growing spring or winter wheat. Looking for an inexpensive solution, the scientists in MSU's Department of Animal and Range Sciences are conducting experiments to see if sheep are feasible for controlling weeds and stray wheat on fallow fields. If grazing proves successful, Montana farmers will lose weeds, and Montana sheep growers will gain a food supply.
The experiment at the Fort Ellis Research Center began four years ago and compares the effectiveness of sheep, chemicals and tillage practices on weed control and grain yields the year after the summer fallow treatments. Results so far show that grazing doesn't affect grain yields for spring or winter wheat. It also does nothing to reduce grain quality, weight or protein content. Sheep may have a minimal impact on soil compaction, but the winter freeze and thaw mitigates any differences among fallow treatments. Grazing takes more time than spraying or tilling, but grazing is better than tillage for preventing "volunteer" plants in future crops.
"Weeds and volunteer wheat make really good feed for sheep," Goosey noted. "A lot of times, the weeds have 20 percent crude protein which is very good."
Hatfield said the researchers hope to continue the experiment for six to eight more years. That will give them enough time to study the full impact of grazing, as well as other crop rotations. It will also allow them to pursue other questions, such as issues related to carbon sequestration and the economics of using sheep as weed eaters. How does the cost of fencing, watering and moving sheep compare to the money spent on herbicides and tractor fuel, for example? If grazing works on a small plot, does it necessarily work on a full-size field?
The MSU experiment involves 45 plots, each one-third of an acre. The weeds on 15 plots are controlled by sheep. Fifteen more plots are managed with chemicals. Fifteen others are controlled with tillage practices, tractors pulling plows through the fields. Eighteen plots are fallow after growing winter wheat. Eighteen are fallow after growing spring wheat. Spring wheat grows continually on nine plots.
Approximately 75 sheep, all from the Fort Ellis Research Center, are used for the experiment, Hatfield said. The researchers send as many sheep into the field as necessary to remove unwanted plants in usually two to seven days, depending on the type and quantity of weeds. The sheep graze four to six times per summer, compared to usually four tillages or four chemical applications.
In the early spring, the sheep mostly find volunteer winter wheat from grain that was lost during the previous harvest, dandelions and Downy brome, Goosey said. During the summer, the sheep find weeds such as Redroot Pigweed, common mallow, shepherd's purse and cutleaf nightshade.
Snyder, the hoop-throwing student, said the project has gone beyond being a summer job for her. Hayes and Goosey not only taught her valuable lessons about sheep and research, but they gave her opportunities to present their project at conferences.
"It feels like I take the credit for what they are doing. What they are doing is awesome," Snyder said after winning competitions with her presentations.
The MSU experiment began with a grant from the
U.S.D.A. Pest Management Alternatives Research program. Funding now comes from a U.S.D.A. Four-State Ruminant Consortium grant.
Evelyn Boswell, (406) 994-5135 or
evelynb@montana.edu
Hi-Resolution Images or PDFs Available:
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Erin Snyder looks inside her hoop for plant remnants. If she finds any, she places the samples inside brown lunch bags for later examination. (MSU photo by Kelly Gorham).
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Erin Snyder and Hayes Goosey examine wheat in an experimental plot east of Bozeman. (MSU photo by Kelly Gorham).
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Sheep at the Fort Ellis Research Center near Bozeman help Montana State University researchers in their experiments. (MSU photo by Kelly Gorham).
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