fence crimping

Instructor Kent Solberg led an SFA sponsored fencing workshop near Goodhue, Minn.

GOODHUE, Minn. — Undaunted by a recent heavy snow, John and Jarod Luhman’s cover crops look especially green against the white backdrop. Just over the hill, cattle graze contentedly on the tasty forage.

Not only can cover crops improve the health of soil, they can pull double duty as a feed option for livestock. As cover crops gain in popularity, farmers are turning crop fields into temporary pasture for their animals.

The Luhmans operate 700 acres of cropland to grow organic corn and edible beans. While they have always raised cattle on their farm (appropriately named Dry Creek Red Angus Farm), next year the Luhmans are cutting crop production and increasing the size of their herd.

“Cattle are a little more predictable than hoping you’re going to get a good crop each year,” Jarod said. “Plus we can save money on land rent.”

While cattle rarely develop wanderlust if good food is readily available, some form of fencing is needed to keep them in the desired area. The Sustainable Farming Association conducted a hands-on seminar, “Fence Options for Grazing Cover Crops and Corn Residue,” at the Luhman farm on Oct. 29. SFA Senior Technical Advisor Kent Solberg shared practical techniques for erecting temporary fencing.

Temporary fencing does not involve barbed wire or even heavy fence posts; but relies on electricity to do its work. “An energized fence is a psychological barrier rather than a physical barrier,” Solberg told his students. “You want to train the cattle to stay in the grazing area. Because of their portable nature, they are easy to modify, expand, and can be ideal for a rental scenario. They can be less costly than a barbed wire or woven wire fence as well.”

At the Oct. 24 workshop, participants constructed two different corner assemblies and learned grounding system and energizer techniques. The workshop also discussed the components of an energized fence (braces, line posts, wires, energizers, gates), and how to ensure that the fence will work properly.

“Cattle and hogs are easiest to control with a temporary energized fence,” Solberg said. “Poultry, sheep and goats can be more difficult. Terrain and topography will also play a role in the size and design of your fence. Low, wet areas will require sturdier construction and more maintenance. Hilly ground will require more spacers and tension adjusters to maintain the desired height of the wires.”

Corner support is the foundation of a successful fence and Solberg presented two options. The first utilizes eight-foot, eight-inch wooden posts to anchor the fence.

Solberg recommended starting the post hole with a shovel, followed by a clamshell post hole digger to a depth of about four feet. “You can use an auger to drill holes,” he advised, “until you encounter rocks. A clamshell digger picks rocks out of the hole like a tongs.”

Posts should be kept as vertically straight as possible and the bottom six inches of soil needs to be tamped down to maintain the stability of the post. “There will be quite a bit of tension placed on these posts,” Solberg said. “Tamping the soil inside the hole gives you the best support.”

The other corner system utilizes two-inch PVC pipe which is held in place with six-inch steel augers. One length of pipe is vertical and is supported by a second pipe at a 45-degree angle. “A full corner will cost about $240,” said Solberg, “but it is much easier to install and remove. What’s your time worth?”

Solberg added the wooden posts require a Bobcat to pull them out of the ground. However, some farmers will leave the wooden posts in year-round and simply operate machinery around them. “It’s a nice option if you can work around it.”

While a single wire 36-inches off the ground may suffice to control the livestock, Solberg recommends two strands strung 10 inches apart, 30 and 40 inches off the ground. “The 10-inch space keeps cattle’s eyes from breaking the plane of the fence,” he explained. “If they get their head between the wires and then get a shock, they don’t back up, they go forward … and there goes your fence.”

Farmers raising larger animals such as Holstein or Charolais may want the top wire to be 48 inches off the ground.

Solberg suggested stringing the fence with a 12.5 to 14-guage high tension wire. “It’s a lot easier to take down,” he said. “It will cost 28 to 55 cents per linear foot, but you will be able to recover 99 percent of your materials for future use.”

Posts supporting the wire along the way should be spaced 30 to 50 feet apart, depending upon the terrain. The posts will help maintain the height of the wire.

“I know a lot farmers have a bunch metal fence poles sitting around and figure, ‘why not use these?’ And you can, but you’re going to have grounding problems,” Solberg warned. “I like fiberglass posts the best. They’re cheaper and there are multiple ways to clip the wire to the post. You can even make your own clips out of heavy wire.”

Fence strainers adjust and maintain the tension of the fence. They will also function as shock absorbers should deer run into the fence. On flat terrain, tension adjustment should be available for every half-mile of fence. Adjustors should be used every quarter-mile on hilly ground.

“You want even tension,” Solberg recommended. “Most people have a tendency to over-tension and that requires stronger bracing. Once you string your fence, let it settle a few days before making final adjustments. You’re going to want to loosen the tension in the winter and tighten it when it’s warmer.”

Because of their normally-remote location, temporary fences are powered by a 12-volt fully sealed agri fencing battery. Deep cycle batteries should be used instead of car batteries as they are designed to be repeatedly discharged and then re-charged. A fully-charged battery will operate a fence for about eight weeks.

Solberg recommended maintaining a pulsating current of 7,000 volts through your fence. The static shock from touching a doorknob is 5,000 volts. If the fence is not properly grounded, the shock may not be as powerful — or even felt at all. “I would suggest a minimum of three ground rods on a fence,” he said. “The ground rods help increase the voltage. Some operations bury pipe along the fence for better grounding.”

“Again, this fencing is not designed as a physical barrier,” Solberg reminded the class. “You want the animal to get a shock. And good voltage is important for that — especially in the winter when animals will have a heavier coat.”

For those considering a solar-powered unit, Solberg said it would take two 32-watt panels to keep the battery charged in the summer. “But when the days get shorter,” he glanced at the overcast skies above, “how much power are able to generate? Plus, it adds a bit more expense to your fencing operation.”

Tearing down a temporary fence takes much less time than the set up, but proper care will make the next set up easier. After releasing the tension on the wire, carefully wind the wire into a coil — being sure not to kink the wire in the process. Kinks in the wire create weakness and the wire is more prone to break at these points. Solberg suggested securing the coils with a zip tie and labeling the coils with the length and location of the fence.

“There aren’t many shortcuts involved in putting up a temporary fence,” Solberg told the class, “but once you’ve done it a few times it goes pretty quick. The time you take setting it up properly the first time is time you will save down the road.” 

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