Researchers Find That Burning
Improves Life Of Barbed Wire

By Colleen Schreiber

STILLWELL, Okla. — Everyone knows that prescribed fires destroy fences. But everyone may not be right.

So say Oklahoma range scientists. Recent research gathered at OSU’s Cross Timbers Research Unit shows that burning actually improves the strength and life of barbed wire — under certain circumstances.

Burning is one management technique that has long proven successful for control of cedar, but for a wide variety of reasons, few landowners incorporate prescribed fire into their management plans. Among the reasons often cited for not using prescribed fire are such things as economic and legal liability, lack of available fuel to carry a fire, inexperience — and fence damage.

Oklahoma State University range scientists have been conducting and researching prescribed burning since the early 1980s. Some of the pastures they have studied had six controlled burns through them, yet there was no noticeable degradation of fences, and they have never been restretched. Researchers decided to establish a research project to further investigate the effect of burning on fencing. The project was initiated by Dr. John Weir, research scientist and manager of OSU’s Cross Timbers Research area.

The Cross Timbers Experimental Range, a postoak, blackjack and eastern red cedar community, comprises 1760 acres located just outside Stillwater. The Cross Timbers was originally homesteaded in the late 1800s during the land run. Old homesites can still be found on every quarter section of land. Back then there were no cedar trees and very few other trees.

In the 1920s and 1930s, many of the homesteaders abandoned their claims. The Bankhead Jones Act allowed the government to reclaim these lands, which in turn were given to different entities. In this case, the government in the 1940s began renting it to Oklahoma A&M and they deeded it to the university in 1954.

Fencing on the Cross Timbers Research area is relatively new. The area was crossfenced in 1982 in preparation for the initiation of a research trial. Several different treatments were established. Testing was conducted on fence that had been burned through six times, twice, one that had a wildfire go through, it and some where no burning had occurred. Researchers also tested some of the original wire still in storage.

Most barbed wire is 12.5 gauge Class I wire. A zinc coating serves as a weather protectant. To be classified as Class I wire, it must have a minimum zinc coating of 30 ounces per square foot. Class III wire has more zinc coating.

All barbed wire, Weir explains, first goes through a 1280 degree lead bath, which relaxes the wire and gets all the stretch out of it. The zinc coating is then applied at a temperature of 760 degrees.

Samples of wires from the various treatments were sent for analysis to the American Society for Testing and Materials, which handles the quality standards for wire.

Tensil strength of the various samples of wire was measured, and ASTM found no difference in tensil strength between wires burned six times and those burned once.

A strip test, which measured the amount of zinc coating on the wire, was conducted on the various samples of fence. One-foot pieces were first washed to remove dirt, weighed and then soaked in a diluted hydrochloric acid solution, which stripped the zinc and left a bare, shiny wire. The wire was dried and reweighed, and a micrometer was used to measure the diameter of the bare wire. That measurement was then plugged into a formula which calculated ounces of zinc per square foot.

Researchers were surprised to learn that fences which had been burned actually had a better coating of zinc than the unburned wire. They learned that heating the wire created a zinc/iron alloy, which actually improved the strength and the life of the wire.

"So what we’re saying is that prescribed fire doesn’t hurt barbed wire," Weir says.

Researchers are now studying the effect of controlled burning on wire that is much older, and that basically has no zinc coating left.

(One admittedly unscientific observation suggests that old wire subjected to a wildfire rusts like rebar in a brine pit, but then the wire in question was old enough to have been freighted to the site by mule team. — Ed.)

In the early 1990s OSU researchers also initiated a research project to study the feasibility of using paraquat herbicide to move a fire through closed canopy cedar-infested rangeland. The research was conducted on the Sam Daube Ranch near Ardmore.

Without adequate understory vegetation, researchers reasoned, getting a fire to move through dense cedar canopies required drastic measures.

Paraquat, a desiccant registered for rangeland and pasture renovation, was used to "brown-out" cedar canopies prior to setting a head fire. For the paraquat treatment to be successful it must be applied in temperatures above 80 degrees Fahrenheit, or its activity is greatly reduced. In this particular instance, the paraquat was sprayed in August in the heat of the summer.

The headfire was set by helitorch a few weeks later. The fact that the controlled burn was conducted in the heat of the summer makes the treatment somewhat more risky. Ideally, the fire carries only over areas that have been desiccated. Other areas are too green to carry a fire.

Despite the risk potential, range scientist Dr. Dave Engle found the treatment to be successful and cost-effective. At $15 an acre, such a treatment is more economically viable than chaining or root plowing.

OSU scientists are also conducting research to determine which is the best month to burn. Data thus far indicates that, on average, January offers more days with conditions that fall within the desired prescription than does March, which is typically when most burning occurs.

Up until 1982, the grazing rights on the research area were leased out. The first research project initiated on the Cross Timbers was a brush study which looked at the effects of two different herbicide treatments on components of an eastern red cedar community.

The ranch was subdivided into 22 pastures of 80 acres. Four pastures were untreated. Eight pastures were treated with Spike or Grasslan, the other eight with Grazon ET, which is now known as Remedy. Herbicides were applied aerially at two pounds per acre of active ingredient. Additionally, four pastures from each of the two different herbicide treatments were burned on a periodic basis.

The study was conducted for 10 years. At the end of the 10 years, researchers found that the pastures treated with the different herbicides but without fire were back to the same level of brush, basically a cedar forest, as when they started.

"The research plan was really designed to manipulate the hardwoods, but turns out it actually released the eastern red cedar," Engle says. "We found that if you kill the oak hardwoods, cedar gets a break."

Researchers found that they could profitably burn every year except on sandy sites. On these sites, generally not enough fuel can be accumulated every year, so researchers burn every third year.

Burning is done in March. Unlike the drier regions of the Southwest, rest following a burn is not recommended. Instead, the area is immediately double stocked for 75 to 90 days. Research has proven that burning is profitable for stocker operators, and if used in combination with double stocking, can produce about a 15 percent increase in gainability.

Burning on these sites, Engle says, costs about $2 to $5 an acre. The more acres burned at a time, the cheaper the cost.

Scientists continue to study the successional stages of the brush, how effective the various controls are and how long the treatments are lasting, as well as cattle performance, effects of fire on whitetail deer, songbirds, rabbits, rats, etc.