Phil Stevens

I have a particular end-of-life use for steel that's rusted beyond any hope of doing something structural. I put all those flaky bits, along with nails and staples from pallets that were turned into biochar, into a bucket with a solution of oxalic acid. This dissolves the rust and I then use the liquid for soaking wood chips and chunks. Then, when those get turned into biochar, the iron oxide forms tiny crystals all over the carbon sponge structure and the end result will stick to a magnet. Iron-enhanced biochar has all sorts of electrochemical properties that are especially useful for cleaning up contaminants, and can even safely break down "forever chemicals."

Ah, stainless. That would explain the shininess for sure, and of course it wouldn't have the ready availability or rock-bottom price of a regular steel one. I'd love to see examples of mild steel drums that have been in service for ten years or more, so if anyone has them please post a photo and a few words about what sort of life it's had.

There is a time-honoured test for vernacular engineering: It's time (and that is cool, because it's a recursive concept that time itself proves the validity of the axiom). The test of time is often downplayed or even dismissed by lots of folks, and I suppose that is a curse of modernity. I sort of had an "Aha!" moment when I first read Nassim Nicholas Taleb's The Black Swan where he explains it as a rule that applies to ideas, but extends to pretty much any application of human ingenuity. For example, one of his personal rules is to only drink things that people have been drinking for at least 2000 years.

Simply put, if you look at a technology or building method that has been around for a while, you will see all that built examples tend to converge on a set of components, material selections, and designs that fall within close proximity to one another. These get imprinted on people in a cultural and even biological context, so that you can show a kid a drawing of a house and they will say "that's a house." In permaculture, the subject of appropriate technology is totally interwoven with the vernacular and the durability of ideas. We tend to use and extend things that are already known to work, because that saves a lot of time in R&D, and also avoids unnecessary expense and material waste.

I bring this up because the basic J-tube RMH has been around long enough to develop a vernacular, and the reason for that is that enough of them have been built and in service for long enough that the community of builders and users can confidently say that it works and is a sensible, cost-effective, safe, and efficient way to heat spaces. This doesn't mean that there's no room for improvement, but most of that has been in the refinement of batchbox combustion and stratification designs.

For certain use cases, the original J-tube is still a viable choice, and this includes a repurposed steel drum (The Drum) as the primary radiator. The reasons are simple and obvious: They are everywhere, can be had for free or very cheap, are relatively easy to modify with simple hand tools, and at the end of their service life they can be safely recycled or returned to the earth (be careful if your soils are already high in iron, I guess).

Every now and then, we see someone looking to improve or tweak the J-tube design. More often than not, the improvements involve metalwork, but we also know from experience (the test of time) that the high temperatures in the combustion core don't play nicely with metals, especially not mild steel that is easy to obtain and work with for the average permie. A lot of these earnest inventors are especially keen to get rid of The Drum. And there are some good reasons for that when you consider aesthetics -- not everyone wants a big old steel cylinder in full view in their living space. But there's a function being served, and anything that replaces The Drum is probably not going to tick every single one of the boxes, because it's not a drum. This doesn't mean that alternatives aren't out there, but it does mean that you're going to give up at least one of the attributes...most likely the cost and relative ease of getting and fitting one.

As a case study, have a look at this cleaning and inspection video featuring an RMH at Wheaton Labs. The Drum in this application has been in service for 13 years and appears to be more than ready to do at least double that, if not more. I think it's been coated with linseed oil, and it's still shiny:

The leggy habit is normal. When I've grown this in the garden it trails all over the place. It's tough, too. The best examples I've seen of it in the wild were along a beach in the southern part of the South Island. It was growing profusely mixed in with grasses and brush in the dunes, exposed to unceasing wind and salt spray. That was also the tastiest bunch I ever tried, maybe because of the salt. This is one of the greens I'd like to eat more of but always gives me that irritation in my throat that I associate with oxalates. I suppose cooking it would fix that problem.

Biochar, no-till, and deep mulching. My soil is a fine-grain silt loam and although its fertility is decent and I've used lots of compost over the years, the big change happened when I stopped digging, started adding biochar, and got into deep mulch with wood chips. Biochar adds structure and aeration that the unamended soil here is lacking, keeping it better hydrated during dry periods and preventing it from getting waterlogged and going anaerobic when it's wet for long spells. Avoiding disturbance helps preserve that structure as it develops, and this means all amendments go on top now - e.g. mulch.

The partial exceptions I make to the no-dig rule are around harvesting root crops like potatoes and kūmara, but even with these I don't have to fully dig a bed to get what I'm after. I also use a broadfork occasionally to loosen beds and this opens cracks that allow the decomposed mulch and biochar to work into the deeper parts of the soil.

One of the most welcome differences is how easy it is to pull some of the more troublesome weeds like buttercup, convolvulus, and grasses. These used to require tools to get the roots out but now most of the time I can just give a decent tug and they pop right out. Even fennel and dock with 25 cm taproots slide right out sometimes, and those get left on the surface to return all the good stuff that they mined from the subsoil.

We had an abnormally dry and warm November, losing so much soil moisture that lots of paddocks started browning off. This month looked like it might flip the trend when on the 3rd we got monsoon-like downpours...42 mm in a couple of hours. Then we went back to the oven, with a couple of days as hot as we typically get at our peak of summer in the end of January. Now things have gone back to a more typical early summer pattern, unsettled with showers and cool southerlies on the back of them. There's at least some rain in the forecast for almost the rest of the month.

I don't really care much for the "new normal," fam.

I make biochar from old hay, bean vines, corn stover, sunchoke stalks, hemp, and lots of other non-woody biomass. If you're using a flame cap method, you may need to do a lot of stirring to keep things hot. Or you can combine dry leaves with sticks and woody material for a more manageable burn. If you're using a retort, just try to pack them in as tightly as possible so you get a decent yield.

Depends on your requirements, really. Is this for a forklift? You can usually put a slightly smaller Ah capacity LifePO4 in place of a lead acid, but if you put the larger one in you get longer running times.