Hey there everybody
For folks who are unfamiliar with us, we’re a small scale plant nursery that follows permaculture and regenerative agriculture principles. We’ve used tons of wood chips over the years and we’re getting ready to receive more over today and tomorrow. What would you like to know?
Do you pay for the wood chips or do you have some kind of mutually-beneficial arrangement with a lumberyard/sawmill to take them off their hands?
Generally we don’t pay for the chips. We have relationships with a few arborist crews in the area and put in enough face time at Town Hall to be approved as a drop site for the town tree crew as well. Today’s load is coming from our next door neighbors, who are removing a few trees that present hazards to their house.
Sounds pretty win-win to me. Awesome you were able to arrange that with the city, too.
How are the wood chips used? I have read that sawdust isnt really good for a garden.
Are there species of wood that work better than others for your application?
Sawdust or other high carbon/low nitrogen materials do use nitrogen from the surrounding soils - several studies have found that this effect is greatest within ~10mm or so. Materials with high surface area relative to the mass can exacerbate this effect.
We use the largest chips mostly for walking paths and between our rows in the annual veggie gardens. When we find pockets of really fine chips in the pile, we’ll sift those and separate out the super fine material to use as potting mulch for the plants we pot up. The remaining chips are used in our compost piles or as bulk material for hugelkultur style raised gardens.
As far as species selection goes, there’s not much preference. I think a variety of species gives the widest array of nutrients as they break down, which will in turn support a wider array of plants and animals making use of them.
I’m assuming it’s for mulching. Wood chips have different effects on the soil than sawdust because sawdust has a much greater surface area.
Almost all species of tree work well as mulch. But usually you get mix anyway.
We definitely use them for mulching but also as path material, as bulk carbon for compost, and as material for hugelkultur systems.
Have you tried your hand at biochar? I know composting the chips for mulch is high value in a farm operation, but a few tons of biochar can work like a permanent upgrade - improving the soil permanently with one addition - though ongoing permaculture operation continues. I am about to make a biochar cooker out of two steel barrels - inner fuel chamber and outer draft shell. It would probably be more effective with wood scraps than chips though - some air passages through the fuel.
To test it out for myself, I made a miniature version documented at https://github.com/jcadej/TLUD-biochar-reactor (uses a gallon paint can for the fuel chamber. You could test it small and see how it does with wood chips. When I make my bigger version, I will add it to the github project. My rough idea is to cut one barrel down the side and squeeze it smaller and bolt it so it fits inside the other.
We have! We set aside chips to offset our fuel wood usage, and place them in stainless steel serving trays that fit in our wood stove. That’s something we picked up from Sean Dembrosky. I’ve experimented with them in a pit cone style as well but once the coals are raging it’s a good deal of management effort to keep feeding it to prevent it turning to ash. It’s difficult to come across barrels around us apparently, and I’d prefer not to buy them in while I have other options. That said, we do have feelers out for them so fingers crossed I can do some trials like that as well.
I agree that the lack of air space may cause a problem for the pyrolysis in a retort system.