Wednesday, 13 August 2008

Ashes to Ashes

In The Garden

Green with a gun has suggested using the ashes on the garden. I have until now avoided this, recalling warnings we were given when first starting out in gardening that it would alter the pH of the soil and damage it's structure. In the interests of finding the facts and deciding whether we really do have a winning solution I thought it worth investigating some more.

Research across a range of sources reveals the following elements may be present in wood ash, with quantities being dependent on the wood burned, and the ground that the tree grew in. In all cases hardwood ashes have more nutrients (and more ash) than softwood ashes. The values below are all from Northern hemisphere sources, and there's a chance our local Eucalyptus would come up with slightly different numbers.





15% - 30%

Generally in the form of calcium carbonate. This is the same stuff we get in lime, which is used to raise soil pH from acid towards alkaline.


3% - 9%

In the form of potash


1% - 3%

As phosphates.


1% - 3%


0% - 1%



A number of the trace elements are often classed as “heavy metals” and considered to be pollutants rather than valuable nutrients.

According to the PDF:


wood ashes are 40% - 50% as effective at altering soil pH when compared to lime. The other sources indicate that the constituents of ashes are water soluble therefore fast acting, in contrast to lime which takes longer to do it's job.

All sources indicated that wood ash should only be used on alkaline soils, and if using large amounts pH should be tested every year or two.

A number of other warnings were supplied, paraphrased, condensed and/or summarised below:

  • Don't use ash at the same time as applying nitrogenous fertilisers. The fertilisers will gas off the nitrogen as ammonia in the high pH, so you're wasting resources. Wait for a couple of weeks for the ash to do it's thing then apply the nitrogen.
  • Acid loving plants should not have wood ash applied to them e.g. Blueberries.
  • Alkaline should not have ash applied to them, and neutral soils should only have it applied very carefully in small quantities.
  • Ashes should not be applied where potatoes will be put as they may promote potato scab.
  • Don't use ash from stuff other than wood. You never know what you'll get.
  • Don't use ash on your seedbed at time of planting or on seedlings, ash salts are quick acting and relatively strong, so will burn the seedlings.

Another use for wood ash is as a pest control. It can be liberally dusted over infestations of pear and cherry slug to great effect. It was the solution of choice applied during my childhood, and I recall with some trepidation the act of spreading the stuff around.

Some representative sources on wood ash in the garden:


Totally Practical: Wood Ash

Wood ashes from your yule log can help your garden grow

Use caution with wood ash on your lawn and garden

Wood Ash in the Garden

WOOD ASHES - How To Use Them In The Garden

Is Wood Ash Good for Garden Soil?

In Soap and Fuels

Wood ashes (from hardwood trees) can also be used to make lye. Lye is generally made by soaking water through a barrel (with a perforated base) of ashes. The stuff that comes out the bottom is lye water, and needs to be concentrated for use by boiling off the excess water. This is pottassium hydroxide, rather than sodium hydroxide. This is good news if you're looking for a complete on-farm process for making biodiesel, as pottassium hydroxide is the stuff that is used to make ethanol-ester biodiesel, and ethanol can also be made on-farm, unlike methyl-ester biodiesel (which uses sodium hydroxide) See the following if you want to know more:

Making lye from wood ash

Ethanol biodiesel

A comprehensive guide with pictures covering soap making from lye is available at:

Traditional Soap Making

Another blog indicates that soap from potash lye is a jelly or soft soap, and requires hardening up with the addition of table salt if that is the aimed for product. According to the resource hard soaps are made with sodium lye.

Making Pioneer Soap

Wednesday, 6 August 2008

Plans For Drums And Other Melodies

Back to the mundane world of pseudo-farm life for a post.

I've got a couple of plans fermenting at the moment, thanks to the gift of an apple bin full of 20 litre drums. Nothing like a source of raw materials to inspire all sorts of ideas. Hopefully not a case of having a hammer and everything looking like a nail...

Project number 1 is a charcoal and ash separation plant. I've been separating the charcoal and ash from the house fireplace so that I can make use of the charcoal in the forge. It's a messy job using a scrap of mesh over a bucket, so this little bit of work should make it a whole lot more efficient. The picture below shows the main cradle, there will be another similar one beneath it without the mesh windows. This will catch the ash and channel it into one drum, the charcoal will go out the end into a second one.

I'm still toying with the idea of grading the charcoal into two lots, those pieces of a size to be useful in the forge and other smaller bits that can be used in the garden as biochar. That will involve a very fine mesh in the upper window and a larger one in the lower window and some modifications to the catching cradle beneath to allow a second drum.

All that needs to be done now is find a use for the ash. At the moment this is being stored in a feed bag in the shed. With the exception of turning it into lye and hoping I can get hold of enough fat for soap I'm currently at a loss for ideas...

The second project will be a roller that I can drag behind the ute to compact road base. We've got quite a bit of road building to do out at Lyndhurst, and I'd like to do the early stages of it using hard work and the ute if possible. The plan is that we'll get truck loads of local road base dropped in the rough area, grade it out fairly level (now there's a project, building something to allow this task to be done with the ute!) and then roll it firm with the roller.

I've previously built a person powered roller by punching a hole in the bottom of a drum, fixing a bit of gal pipe centred through the drum, liberally greased, and then filling it with concrete and basalt rocks. A series of these that can be slid onto a longer pole and then hooked into a harness to be towed behind the ute should work well enough. I've also considered using two 44 gallon drums to do it, which would produce a better end result, but such a contraption would need to be made on-site as transporting the finished product out there would be tricky, to say the least.

In other news, and other plans, we've finally settled on a basic plan for moving forward overall. It was stressful for a time there trying to figure out the best way to juggle all of the competing demands to try and get ourselves out onto the new block. We've given up thinking about a full blown shed at this point, our outgoings so closely match incomings that having the resources to do that isn't going to happen for some time.

Instead we're going to get a shipping container moved out there, which is an economical means of securely storing the majority of the “junk” (resources!) currently in the shed. We will also be moving the site office out there and working on rigging it up as my office. This should involve a phone line and enough power for a single light and a laptop (assuming I can fit my current systems onto a laptop and run them with sufficient speed and reliability) The laptop should last for three or four hours on a charge from home each day, then continue with a top-up from whatever alternative power system we can implement for the remaining hours of the working day. We'll probably need a bit of power for the actual phone and answering machine, I don't really fancy going back to the old tin can catch me if you can style of communication.

Once we know I can work out there we can move into rental mode. We've minimized the stuff we need to cart around, and removed the inconvenience of re-establishing a home office every time we need to shift to a new rental. Rental mode means selling mode. We can stick this place on the market and get into the rest of the project. The added bonus will be that if I'm working out there daily it will be easy to water a few trees in the morning or evening, so we can start to get some real plantings going on out there.

Once we've sold this place we'll be in a position (as long as the economic sphere keeps it's spokes in place for a while yet) to build and kit out a shed for temporary accommodation. Then it's on to building the house itself. For the shed we are thinking a rammed earth construction. We were going to go with a skillion roof for ease of sticking it together, but sizing the timbers on that for a decent span leads me to believe it would be cheaper to go with a gable type roof. I've acquired some curved I-beam that would make a nice roof shape, just have to find some way of calculating spans and designing webbing to suit. Should be fun :-P

It's a grand plan, ambitious and all that, but I figure if I can build the charcoal and ash separation gizmo then anything is possible!!