I’ve been setting fence posts the last few weeks, getting ready to stretch another line of field fence. I’ve chosen to do a ratio of one wood post per 9 metal “T” posts. The wood posts are 4×4″ treated, and the T-posts are 8′ heavy duty ones, driven into the ground 3 feet. I’m spacing them 12′ apart. This seems to be strong enough, and balances economy of materials with the need for robust fencing. But, I feel very unsure about what the “right” numbers are, because there is so much varying advice and evidence of application.
One thing I do value is the ability of the fence to “spring” a little bit. Knowing that when working dogs, it’s possible livestock might, ah, occasionally get run into the fence full-boar with a young dog in hot pursuit, I don’t want it to be as hard as a brick wall when they hit it. That’ll either break the fence or break the animal, one of the two! This fence does seem to have good flex, but seems strong enough to resist my hardest pushing, and then some. I’ll report back if I regret any of my decisions once dogs and livestock put it to the test!
I’ve chosen to put concrete around the bottoms of the wood posts. This is a subject of debate for many too– concrete makes them a bear to get out, if you ever need to. And, it’s tough to say whether concrete concentrates water around the post more, making it rot sooner than well-drained soil would. But, the deciding factor for me was, my neighbor Bob, a long-time farmer, warned that if you don’t use concrete in the flood plain (which is where the pasture is), you could find your whole fence afloat when the water comes. He speaks from experience, apparently, so I’m going with his advice.
A handy tip I found in a book is to screw galvanized bolts about halfway into the posts where they will contact the concrete. This binds the concrete and post together, so that the post cannot slide or twist within its concrete shell. Here (left) is what I’ve been doing on the bottoms of my posts.
The wood posts are fairly easy to install since I have a post hole digger on the tractor. Tinkering with getting them aligned with the string line is the biggest hassle. The T-posts, I only drive in barely by hand using a fence post driver. When I have a whole line in, I mark the bottoms at 5′ tall, then drive along with the tractor, and push them in down to their marks using the tractor loader. My dad gave me that tip. They go in “like butter” this way, and it sure saves the hard labor of fence post driving!