Wood Ash in the Compost works GREAT

[Gary350]

Over the past 35 years I have noticed every time I put wood ash in my compost it speeds things up very fast. Yesterday I learned why.

Wood ash is loaded with LYE, it is a very strong BASE that will eat up the organic material.

When I sprinkle several hand fulls of wood ash on my 3 foot pile of compost then water it with the garden hose once a week it decomposes twice as quick.

[rainbowgardener]

Depends on what your goal is. If the goal is just to reduce volume of organic materials fast, that works. But I don't have so much organics to get rid of and I want to produce as much volume of compost as I can. So slower decomp leaves me more compost. And being so basic, wood ash will make your finished compost quite basic (high pH). If you want to alkalinize your soil, that might be a good thing. My soil is already too alkaline, so I am very careful with how much wood ash I put in my compost pile, very small amounts.

[tomc]

When I lived in new England on limestone starved soil, adding wood ash (from unpainted and untreated wood) was a welcome addition.

If I lived in the southwest with every kind of salt issue (and alkaline soil) I might be much less willing to use wood ash in my compost.

There is an old phrase that applies here; "hauling coals to Newcastle".

[Gary350]

When I lived in Tennessee I had a lot of tree leaves. I could rake up a pile of leaves 6 feet deep 20 feet across. After mulching them with the lawn mower volume was reduced by 70%. I would haul chopped leaves to my compost 1 large trash can full at a time then sprinkle 2 hands full of wood ask on it. My compost was 5 feet across 4 feet deep and I had it piles up 6 feet high. All the extra would go in large 30 gallon trash bags. By spring the 6 ft pile was 2 ft high and looked like wet potting soil with all the rain we received. The leaves in the trash bags looked like dry potting soil. Without the wood ash it did not compost as quick and still looked like leaves in the spring. TN soil is 6 ph.

You can do the same thing with Ammonium Nitrate in the leaves. By spring it looks like some really nice potting soil.

Wood ash is free I have plenty in my wood stove but Ammonium Nitrate was $20 per bag.

Now that I am in Arizona I need the compost more than anything. Soil here has no organic material and no food value for plants. Soil and water in AZ are both 8 ph.

[PaulF]

My soil has a pH of 8.4 to 8.6 so wood ash is not what I want to add to the compost pile either. That is why a good soil test is a requirement. It is a good thing to know your soil and what it needs for balance.

[rainbowgardener]

My soil is 7.5 - 8 pH, which is why I put very little wood ash in my compost.

[DoubleDogFarm]

Depends on what your goal is. If the goal is just to reduce volume of organic materials fast, that works. But I don't have so much organics to get rid of and I want to produce as much volume of compost as I can. So slower decomp leaves me more compost

"more compost" Do you have some information to back this up.

Eric

[rainbowgardener]

Well, not exactly, certainly haven't really done the research to back it up. I'm basing that opinion about what I have read about some of the methods of quick decomp, like BSF, and tumblers, which seem to be saying that the amount of material is so drastically reduced. My warm to cool composting seems to leave me with maybe 1/4 the amount of material I started with (eyeballing), which sounds like more than what people are talking about.

[DoubleDogFarm]

I don't really compost so it's more of curiousity than I don't believe it.

If you take two logs of equal volume and burn one, leave one to decompose, I could see that. Not sure it's true with cold vs. warm vs. chemical composting.

Eric

[rainbowgardener]

You don't compost?!

[toxcrusadr]

The conversion of organic matter to humus is a biological process, not just chemical, and if a strong base can speed that up somehow, it would be news to me. Not that it can't happen, I just don't know how. It is not the first time I have read accounts of ash + leaves making nice compost.

It would make perfect sense that ammonium nitrate would speed things up since leaves are a brown, low in N. Feed it N and decomp speeds up. Ash has no N. If it speeds things up it is through a different mechanism.

I can imagine some mechanisms. Strong base might chemically break down cell walls and begin to hydrolyze carbohydrates, proteins etc., making them more available to microbes. I would have assumed that very high pH would hinder microbial growth, so the benefit is not worth the cost, but perhaps the alkali reacts away rather soon and the microbes can then take off on the partially digested stuff as the pH returns toward neutral.

Or, it could have to do with other nutrients besides N. Such as P or K. P is a 'limiting reagent' in the biosphere, and a slug of it could conceivably boost microbial growth.

I do have huge leaf bins, and since they are oak and hickory mostly, they are going very slow. I burn wood and have plenty of ash, so perhaps I will try this in a controlled fashion on two identical piles next year.

[Ohio Tiller]

I don't really compost so it's more of curiousity than I don't believe it.

If you take two logs of equal volume and burn one, leave one to decompose, I could see that. Not sure it's true with cold vs. warm vs. chemical composting.

Eric

Look at it this way if you fill a 55 barrel with leaves and let it rot down for a year you might have a 1/4 of a barrel let it go for another year and you might have an 1/8 of a barrel. longer they rot the less you have.
Add things like Lye and it just makes it smaller faster.

[ElizabethB]

Gary - wood ash does reduce your compost pile but I am like Rainbow. I want as much volume as possible. I am also concerned about raising the pH with wood ash. My soil is 6.5 which is perfect for my vegetables and herbs. I use elemental sulfur on my hydrangeas and blue berries to lower the pH. If you are happy with the end result then go for it. The pH issue is my biggest concern.

Good luck and Happy New Year

[Bobberman]

My dad was the leaf guy. Every year when I was about 12 the township leaf trucks would dump leaves in our 100. by 100 garden!The leaf piles were 4 to 5 feet about 15 dump truck loads. We had the garden plowed in the spring and my dad used a lot of lime. He had the best lettuce every year! The soil was great and full of worms. We also had 50 chickens so the manure was also added to the leaves! He would make as layer of leaves and chicken manure and cover it with a foot of dirt and plant his lettuce in march and had the earliest lettuce that we gave to everyone! Black simson lettuce was his favorite! As for me I think pine needles work in a compost since it helps airate it!

[rot]

..
All things in moderation I think. Since I'm less into producing as much compost as I possible can and more interested in recycling or digesting, if you will, what I can, I will apply ash to compost when I need to get rid of it in thin layers. Haven't had a problem.

I suppose the pH thing is a concern but my other concern has been the smothering effect of dusty ash. By rights, since it is almost pure carbon and broken down as much as it gets by the fire, I look at it as applying carbon and by spreading it through out the compost pile, it gets spread around a bit when I apply the compost to the garden. the composting process nullifies the pH effect so I don't worry about it zapping any particular piece of ground.

I get rid of the ash without much of a mess and everything seems happy.

to sense
..

[toxcrusadr]

Unless the fire is extremely inefficient, ash is mostly minerals rather than carbon. There will be charcoal bits of course, I get them even in ash from my very efficient woodstove. But if we're talking "ash" not charcoal, it's mainly oxides, carbonates and silicates of Ca, Mg, Fe, K, P and a host of trace minerals.

Composting definitely takes the pH toward neutral. I don't know how much ash you'd have to add to overwhelm that effect and end up with alkaline compost. Then you'd have to factor in leaching if the pile is not covered.

Ideally, we should all be leaching out the alkali materials to make soap, and then the ashes are neutral, so right back into the soil!