Installing Fence Posts on the Farm

Our high tensile fences in the pastures are strung on wooden fence posts, each sunk four feet deep. Over the years we’ve slowly added permanent fences throughout the farm. We’re inching our way to the finish line, this year adding posts in some of the back pastures.

Here’s a video showing the equipment we use for installing our fence posts.

Transcript

Hey, I’m Dave, your farmer from Wrong Direction Farm. Today and yesterday I’ve been installing some fence posts out here in the back pasture. So we use a rental piece of equipment for that. It’s a post pounder. This one’s actually a newer model that the rental place has. It has a vibratory head, so you put it on top of the fence post and it just vibrates it right into the ground. We sink our posts about four feet deep. Digging these by hand, or even using an auger on the back of a tractor, they always get hung up on rocks. So we found that a post pounder is really the most efficient and effective way to get posts into the ground and, you know, have them anchored there for the long term. So it’s always a big job to get the posts in. We try to gang up a bunch of work to do at once when I rent this equipment to make the best use of the rental fee. And then afterwards I’ll go out here with some galvanized wire and start stringing it up between the posts and get some more fences up.

I’ve dug plenty of fence posts by hand, and I’ve used post hole augers. But both methods are slow. And with all the boulders in our soil, this is frustrating work. So instead, I use post drivers. Drivers get the job done in a fraction of the time. Importantly, because the adjacent soil hasn’t been disturbed or backfilled, the posts are more likely to remain in their original positions without canting or heaving over time.

Installing posts using the older machine in June 2018

Above is a picture from several years ago when I was installing posts using a older model machine. This one lifted a heavy weighted section high into the air and slammed it down. It worked, and I used it for many hundreds of posts, but it had some drawbacks. It would occasionally shatter posts, sending large log-sized sections flying. And then of course there’s the general risk of heavy weights crashing down near the operator’s head, shoulders, and arms. There’s a family story of Rachel’s grandfather crushing his hand with one of these. That always gives me the shivers just thinking about it.

The business end of the machine. That plunger shaped cap is connected to a high speed impact head.

The newer machine employs a vibratory impact head instead of relying on brute force. This is a significant improvement. The slammer-type drivers would often cause the posts to jump around a bit before sinking them. That behavior was particularly troubling on steep slopes, where the base of the post would often slide downhill before embedding into the ground. The vibratory machines allow for superior placement precision. Another advantage is that when working with large diameter end posts or whenever driving into hard ground, the vibratory switch can be latched into position and the operator can walk away while the hydraulics keep on hammering.

With all these posts set in the ground, the next task will be stringing all the high tensile wire. This week I set up a couple of small sections of wire. But with all the other winter projects going on, I anticipate that the remainder of the job will have to wait until next spring.

4 Comments on “Installing Fence Posts on the Farm

  1. What are your thoughts on the toxic chemicals entering your soil from putting pressure treated posts? There are now many alternatives, e.g., metal (galvanized pipe) and PVC (timeless fence) posts. Which one do you think is more damaging to the soil? Do you see difference in plants or live stock behavior near pressure treated posts? Maybe put a dozen of them close to each other (without fence) and see what happens to the ecosystem.

    • In our situation, the best posts are black locust because of their natural rot resistance. Locust posts can be brittle, but if the log itself is free from stress cracks, the wood can last most of a century in the ground. We started a small locust plantation, so I hope some day to have our own renewable supply of fence posts. We sink a fence post every 75 feet along a fence line, so eventually we’ll need a lot of fence posts.

      Some of the alternatives to wood might work in other situations, but I have moved away from using them. Steel posts are inappropriate for use with electric fences. The insulators inevitably slip or break, or sometimes enough wet foliage bridges the gap between the wire and the post, and suddenly the whole fence is shorted to ground. Plastic posts of course are self insulating. And even wood posts offer enough impedance that they won’t drag down the voltage significantly. I no longer use steel posts at all. They are fine for page wire or chain link fences, but not for electric fences.

      Plastic posts, both the PVC and the composite varieties, have their place, but I’ve moved away from using them. The PVC posts are particularly flimsy and I haven’t met any farmer who is really happy with them. Composite posts have proven more durable than PCV, but ten years in I’m finding that I need to replace many of mine. I think this is just the wrong climate for them. In less snowy places, or in places with dry snowfalls like the Dakotas, they probably are more appropriate.

      With the plastic posts, we have trouble with them slewing, bending, or popping out of the ground. Because we have such heavy snow, and especially because of the way snow drifts, we often can find snow over the tops of fence posts during the winter. When this happens, the snow pack will frequently ice up. As this snow subsides of the course of months, it exerts a tremendous weight on the fence, causing the plastic posts to deform. Also, when this happens in the spring when the ground under the snow pack is thawing and wet, the underground portion of the post can actually slide through the muddy earth and resettle into a permanent angled position. We’ve also found that when the wire is properly tensioned, even very slight changes in terrain can create enough downpressure to push plastic posts into the wet ground during freeze-thaw events because of their relatively small diameter. This has caused some of our plastic posts to have hot wires that used to be 12″ above the surface to now be in contact with the surface. Likewise, any plastic post in a depressed area can pop out of the ground unless we install extra duckbill anchoring.

      Then there are fiberglass posts. We’ve also tried them. They share most of the same pros and cons as the plastic posts. They do have better stiffness characteristics. They are obnoxious to work with because they are so hard, and I hate the fumes when drilling and cutting them. But the worst thing are the splinters. Eventually, even with coatings, they become terrible splinter hazards. For all the patches of tiny splinters I’ve had in my hands, I hate to think of what happens when a cow’s soft nose brushes against one of these.

      For pressure treated wood, I agree that any chemical should give us pause. Although the testing for ACQ (alkaline copper quaternary) treated lumber indicates a much safer formulation than the old posts that were treated with CCA (chromated copper arsenate), both in terms of its toxicity and its leaching potential. It would be interesting to do the experiment you proposed. In the meantime, I haven’t seen any indication of a change in plant species or a difference in foliage growth immediately adjacent to a fencepost versus another spot thirty feet away under the same fenceline.

      • I knew of a friend who went to his great grandmothers farm in West Viryand they were pulling out black locust posts that had been in the ground for 150 years that were solid enough to burn for heat

      • I haven’t encountered anything that old, but I don’t doubt your story. It’s a remarkably durable wood.

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