Jim Russell (standing in water) explains the crossing at a September field day that attracted 75 people.

ISU professors and graduate students work together to install a length of Geoweb fabric for a stream crossing.

Jim Russell (standing with red hat) oversees crossing construction in Spring 2005. Beside him is Tim Good, farm superintendent for the project.

Iowa State University animal science professor Jim Russell has adapted the unique mesh product to create stream crossings. The crossings will be used primarily by cattle in pastures near Rhodes in Marshall County as part of a three-year research project that began in 2005 and is supported by grants from the Leopold Center and the Iowa Department of Natural Resources.

Stream crossings can be very important in rotational grazing systems. Cattle are allowed access to water when there is a natural source, eliminating the need to construct expensive water lines, wells and pumping systems. The crossings also must be cost-effective to install and maintain. An ideal crossing would not contribute to soil erosion or water quality problems.

Russell agrees that it might be a tall order, but he's waiting to see how the Geoweb® performs.

"Two days after we started grazing, we had a four-inch rain, which washed out our water gap fences but the crossing held," Russell said. "It will be interesting to see what happens in future years."

Two crossings built
Two 80-ft. long by 16-ft. wide crossings (which includes ramps on both sides) extends through Willow Creek, where the stream is about 10 feet wide. In the streambed, a section about 16 ft. wide and 20 ft. long was excavated to a depth of 9 inches. Underneath the Geoweb® is a layer of geofabric, then the web, which is filled with rock to bring the crossing to the level of the streambed. Without the labor, cost for each crossing was about $4,000.

A bigger question remains over the impact of livestock grazing practices on phosphorus and sediment levels in pasture creeks. The project is aimed at offering an alternative to help beef producers stay within total maximum daily load (TMDL) water quality standards as set by the U.S. Environmental Protection Agency. Although adhering to TMDL level currently is voluntary, the Leopold Center and the Iowa DNR are funding Russell's research to find ways to decrease non-point source pollution and create more effective grazing systems.

"We found in our earlier research that what one producer calls continuous grazing, another calls rotational grazing and yet another calls intensive rotational grazing," he said. "We really needed to see the impact of various grazing systems on the landscape."

Three systems evaluated
The project evaluates three treatments, each replicated twice on 180 acres divided into six 30-acre pastures, all dissected by Willow Creek. The project involves 90 fall-calving cows, with 15 cows assigned to each pasture.

Treatment 1: Continuous grazing; cows have full access to the stream.

Treatment 2: Continuous grazing; stream access limited to crossing. Rest of the stream is fenced off as a 110-ft. riparian buffer on each side.

Treatment 3: Intensively-managed rotational grazing in smaller paddocks; cows do not graze in riparian paddock longer than four days or to a grass height less than four inches (alternative water source also available).

The project includes a number of measurements:

• streambank erosion using fiberglass pins that are checked monthly for changes in length exposed or covered, also a ground-based laser radar that scans the bank in every pasture in spring and fall;

• stream morphology, determined by taking digital images that show roughness and shape of the bank three times during the grazing year;

• vegetation and cover to determine the amount of bare soil along the stream, 110 feet away and in the uplands, also distribution of livestock manure and the forage height and mass in those areas;

• observations of animal behavior recorded every 10 minutes for 12 hours on two consecutive days twice a month during the summer grazing season to mark (with the use of GPS units) where the largest group in the herd is located, distance from the stream, and when they defecate and urinate; and

• stream flow and weather conditions.

First-year observations
Russell offers these early observations.

"In the early to mid-summer months, when the temperatures were in the high 70s and 80s, cows in the continuous grazing areas with full access to streams spent more time in the stream, but still was not over 10 percent of the daylight hours," he said.

"Where cows only had access at crossings, they used the stream for water but that's about all they were doing, even in the shade. We're not sure why, but they may be uncomfortable with the rock or electric fence in the lane," he said.

"Even on the hottest days in August, cows on all treatments did not spend much time in the stream. They were on top of the hills in the shade, catching the breeze, so wind may play a major role in cattle behavior," he said.

A field day in September attracted 75 people, which Russell says is a good sign that producers are interested in learning about alternatives.

"The crossings are just another tool available to producers," he said. "Grazing can be environmentally responsible but it requires both an investment of time to manage and funds to set up the system."

Russell specializes in forages and grazing, and is principal investigator for the project. Working with him are three ISU animal science professors: Daryl Strohbehn who specializes in cow-calf systems, Dan Morrical who specializes in grazing management, and Wendy Powers who specializes in manure management and environmental quality; along with John Kovar from the National Soil Tilth Laboratory; and John Lawrence from the Department of Economics.

A farmer's perspective
Bruce Carney, who moved to his family's farm near Maxwell in 1996, has worked hard to set up his rotational grazing operation. He maintains a 125-cow herd on 100 acres of permanent pasture and 60 acres that he rents from neighbors. He rotates among a number of paddocks, using techniques he learned in ISU Extension programs, seminars and field days. And he's learned from Russell's project.

Bruce Carney

"I struggle most with water," he said. "A pasture is no good without water and I'd prefer to use my creeks simply as a back-up."

Drawing on his experience as a construction superintendent, Carney has installed an extensive water system and about eight crossings, built with recycled concrete, 2-ft. culverts and rock.

"My cattle don't spend too much time in the crossing because they don't like the rock," he said. "And so far my crossings are holding up very well."

Carney also has built a spring-fed cistern with 3,000 ft. of pipeline and five hydrants. In another area, he has installed 5,000 ft. of water line from an existing well that allows him to include his entire farm in the rotation, including hay and crop ground. Water from a neighbor's field tile also is piped to a holding tank, which cattle tend to use rather than his creek, he added.