old mill by-product safe for Hugelkultur?

I am going to start a few hugelkultur beds with some old fence posts and I have some considerable space where we used to have a hog fuel riding ring. The hog fuel has not been replaced for at least 15 years- would this be safe to build the beds on?

Here is a picture to show the hog fuel (it's the only pic I have of it).

What is hog fuel?

It's basically just a by-product of mill work- a mixture of wood chips, bark, etc. People used to be concerned that chemicals from the wood would leach out but I'm not sure how accurate or realistic that concern is. I have never quite understood what chemicals and from where. Perhaps it is an unknown mixture of different woods which would be a concern in terms of potential toxicity?

In the picture, the hog fuel is the dark area covered in wood with the small stack of fence posts.

is the land always barren around that pile?

I would add alot of manure even hot manure then after that add the hugelkultur on top, with alittle bit of extra manure.
The hog fuel is just a high carbon area so all the nutrients are being used up by mushroom/fungus eating it. Depleting the Nitrogen so nothing can grow.
So if you add manure it will re-balance the nutrient ratios.

Sophie,

do you know if it is only bark and and chipped wood? I would not be to concerned if it is only that. However, I would be more concerned if there was all sorts of treated wood and glued wood.

If you have some friends in a soil science department in a university close by, you could maybe get them to test the soil.

The local sawmill has said that it is only unprocessed wood chips and bark. So nothing else should be in it at all.

I don't have a ready source of manure anymore- haven't done for about 7 years. I have a massive amount of 7 year old manure and fresh chicken manure.

That land is currently not being used but isn't barren (that pic is from our wettest and coldest time of year). It used to have horses and occasionally cows on it. We tore down the fences last year and still have not come up with a use for it that we can agree on :-/ It does need some serious tending if it is to become crop productive though.

Did you check the size of the hugelkultur beds that Sepp Holzer did at the event in Montana last year? That might be an option for this area. From what I gathered when the hugel raised garden beds are ~6 ft tall they are much more awesome.

For the nitrogen issue mentioned by S Bengi, perhaps you just have to plant different seed mixes and see what works. My guess, and I am no expert, is that after 15 years the nitrogen binding is not as much of an issue.

There was not a huge amount wood in the hugelkultur that Sepp had built here in Montana as he likes to use whatever is on site if possible. He used a lot of organic matter and brush from the wetland area, then covered it with soil.

I've looked around a bit for the article on his Montana build but haven't been able to find it. I'll keep looking

I did find illustrated instructions on his style of hugelkulture and it looks like there is typically a considerable amount of wood making up the base for the beds. Followed by an inverted layer of sod and then a layer of humus.

There was some mention that he does not like to provide stone or wood borders but there was no rationale for it. Does anyone know why this is a preferred method?

Here is a thread at Permies about Sepp's visit. I point you to the last page of the thread because there are many pictures that give you an idea of the scale of the hugel raised beds. There is also a video of them on page 2 of the thread.

Have you seen Paul's video on hugelkultur? He has footage of the beds in late summer. Pretty cool!