Vinegar washing wood ash

Hey team,

I've been thinking about doing this, as my Payson, Utah soil is quite alkaline, but I don't want to waste my wood ash.

I currently put it in my compost, and there's some neutralization/buffering which occurs because of that, but I'm thinking of doing a vinegar wash before putting the ash into the compost.

Preliminary research indicates I'm not original in my thinking, and the combination will indeed lower pH and form acetate minerals in place of carbonate minerals. Indeed, some experiments, using fermentation, have shown an interesting outcome: highly acidified (pH 4-5) minerals with significantly increased electrical conductivity.

Initial research also indicates success simply pouring the slurry over soil.

Any of you have any thoughts on the matter, or experience neutralizing the alkalinity of wood ash, or anything else relevant?

If the goal is to add the wood ash to a compost pile a small amount of vinegar might be okay.

Large amounts of vinegar added to a compost pile might harm or kill the beneficial bacteria and fungi that work to break down organic matter in the pile.

If the goal is to neutralizes the ash then using the vinegar washed ash directly on the soil might work.

People make lye (strong base / alkaline) by leaching water through fresh hardwood ash. So that must neutralize the ash's pH quite a bit.

The question is, do you also lose a lot of the fertilizer components (phosphorus, potassium) in the process.

Douglas Alpenstock wrote:The question is, do you also lose a lot of the fertilizer components (phosphorus, potassium) in the process.

Matt McSpadden wrote: potash was a product produced from wood ash (hence the name) and was synonymous with lye. This material was potassium hydroxide and was used to manufacture all sorts of things, such as alum, saltpeter, soap, glass, tanned leather, gunpowder, paper, bleached cotton textiles, and various woolen goods.

from thread about potash

So I would expect you would lose most of the Potassium. Phophorus is also pretty soluble (that's why we get algae blooms from agricultural runoff). As a soil additive therefore, the wood ash would have little point left I think.

Maybe you could add something acidic that wasn't liquid to nutralise without washing the nutrients out? Lemon rinds? Coffee grounds? You'd need a lot though.

Sulfur is another possible neutralizer.  Not sure what compounds it might create though.

How about urine?
It's slightly acidic.

Gray Henon wrote:Sulfur is another possible neutralizer.  Not sure what compounds it might create though.

Good point. As I understand it sulfur does not directly change pH -- rather it encourages certain microorganisms to metabolize it and excrete sulfuric acid. So this is a soil biota mechanism rather than a direct chemical reaction.

Interesting idea. I've been composting my wood ash straight but the alkalinity worry is real, especially on already chalky soil. What I found works for me is just mixing it in small amounts into the compost as it goes rather than dumping a load at once. The buffering from all the decomposing material seems to keep it in check without needing the vinegar step. Curious whether the acetate minerals hold nutrients better long term than the carbonates though.