Is charring really an effective treatment for ground preservation of wood?

It’s interesting reading the interpretation of the study from the OP. I read a lot of them and it’s true, they have to be read with some context. But this is particularly interesting because this was largely done before there was any vested interest in chemical treatment. I mean these posts and treatment tests were done in the 1950s! The more recent tests don’t even include ACQ which is the most common treatment. This is old and presumably less tainted data.

Additionally the posts in most of the study were the same type of wood in the same place. That removes a lot of variables. I really really actually like this study.

The most interesting thing- by far- in the data table in my opinion is that the Osage orange had no rotten posts - after 70 years! In freaking Oregon! Unbelievable! I planted a few hundred pretty close together to try to get some straight poles in maybe 20 years. This seems like the logical step for ground contact. I’m throwing in some black locusts seed this year in the “patch” because it’s awesome but we’ve had issues with borers that might limit the usage.

Well I'm not a trained pro or a PHD but I can tell you by experience that charring wood well help it last longer, the old people in the mountains of Tenn. did it all the time. They well tell you the spring is the best time to do it because the sapp  comes to the surface in the pine trees as the tree cools and remains there and acts as a barrier against water and some insects. I have seen this proven out over time and it does seem to work. But I will add this process seems to work much but on pine, ceder, white pines and trees that have type of sapp.  

Hey Rufus, when you say salt do you mean regular sodium chloride or sodium salt of boric acid (borax)?  I would think borax considering salt increases water retention, though I have read regular salt can be beneficial in preventing checks and shakes (cracks) when drying out green timber.

Hello;  

 This has been working for me::  Treat post  with termite oil , (which can be replaced used crankcase oil from diesel engines). Best to soak in a bucket for at least a week. Then dry in sun , rotating , until surface is mostly oil free. Now wrap bottom part of post in rolled roofing material, secure with galv nails or better. This of course works better if post is round, You can also use old roofing shingles, in layers such that water runs off. Single layer should extend above finish grade by 6 inches. I use fiber glass reinforced shingle material. This stuff can take direct sunlight for decades. On the bottom  of post  I use a block of 1 inch thick plastic cut to match post cross section. Screw nail it in place. The shingle material wrap should extend right to bottom of plastic cap. The idea behind this method is to keep the anti termite oil from leeching out, drying out from contact with soil.  Set post on a brick or flat rock, backfill with gravel. I realize used crank case oil is a bio hazard, but if you do use it thin with paint thinner 50% and let it completely soak in before wrapping the post. For this use,  the blacker the diesel crank case oil is,  the better ...hopefully with shingle wrap the oil will stay inside the wood post for many years and not get into the ground at a rate that is hazardous.

This is TRUE! ...for 1000's of years societies have used this method to preserve WOOD! But... never "hardwoods" because they do not burn easily & when they do burn, it is harder to scrap/clear the char away. So they use "Soft Woods" like Douglas or White Fir!

Most people don't understand the concept or know they don't have to burn & scrap it anymore with propane "Torches"... all they need to do is "Scorch It"!

The concept reason is simple; Scorching Opens the Grains & Destroys anything that leads to DRY ROT!

Yes... Dry Rot is caused by bugs/etc that eat the deteriorating wood... even under the surface of paint or coatings w/ minute pinholes, where water leaks in!

So now the idea w/ these high heat Propane Torches is to Blast it w/ Torches... enough to do what people have been doing for so long and not have to do more than Blacken it to raise the grain & penetrate into the wood to destroy anything that could lead to "Dry Rot" only! ...of course, creosote would do it for the part in the ground, but it's used primarily on things like Railroad Ties... etc to do the same thing!  ...yet today "Propane Blowtorches" do it cheaper, easier and it doesn't take forever... to do like burning it!

Scorch to Get Color Change on Soft Woods like Cedar, Douglass or White Fir and it's cheaper & better than any other method!  

Jay C. White Cloud wrote:焼きすぎ-  Yakisugi

焼き杉 - Shou-sugi-ban

Jumping in quoting an ancient post- excuse me for that. Being quite fluent in Japanese though I often feel obligated to improve the accuracy of translations. Excuse me for that too.

焼杉、焼きすぎ、焼き杉 - are all "yakisugi" this literally means "burnt cedar"
焼杉版 - is "shosugiban" this literally means "burnt cedar board"