Topic: Wood ash, what's it good for, what's it bad for?

[gray1720]

I've been offered someone's ash from their woodburner (quantity uncertain), the last query and advice on here I can find is nine years old so, given the increase in popularity of woodburners in that time, just wondering before I say yes who uses the stuff and on what?

FWIW, I have no idea what my soil pH is like, though as I've never felt the need to test it, it can't be far from neutral (ie most things seem to thrive). Anyone on the Thames floodplain care to offer a view - digeroo, perhaps?

Of course, gardening has changed vastly in nine years, so the old advice must be out of date, right?

Thanks!

Adrian

[ACE]

Just spread it on the plot. But if it has been out in the rain a lot of goodness would have been washed away.

[telboy]

Good for alliums (onions/garlic). Can't think of any harmful uses.

[goodlife]

Yes...just spread it about...though if it is not 'washed' with weather, I wouldn't use it on spuds...it will turn them scabby....but anything else will love it, particularly brassicas and oniony things...and don't give anything that needs ericaceous compost (blueberries etc.) because of the slight effect for soil/compost PH levels.
Or...you can sprinkle it in compost bin between layers of compostable material..composting process will benefit with it (composting worms prefer not so acid conditions)
All little bits of charcoal is very good for the land too...similar stuff, 'bio char' that is now commercially sold for lot of money.

[Tee Gee]

This is an extract I have taken from my website


Wood ash; from a bonfire or wood burning stove is a useful soil improver.

The type of wood burned can have different results; e.g.

Ash from untreated wood has a slight liming action and can be used to raise soil pH.

Ash produced from young sappy growth contains potassium and traces of other nutrients.

On the other hand; older mature wood tends to contain lower concentra­tions of nutrients.

The actual nutrient content of ash varies so precise application is difficult, listed below are a few suggestions;

Where ash contains large particles, it is probably best to dig this in to improve the structure of the soil.

Adding finer ash to the compost heap / bin in thin layers will allow it to blend with other materials.

Alternatively; rake the fine ash into the surface of the soil if you are sure of its content. (See note below)

Note; In the event that some unknown product with toxic properties may have been burned along with the wood, it is probably safer to allow ash to ‘weather’ in a heap for a few weeks, before spreading it around growing plants.


Coal ash; is best avoided because it has a negligible nutrient content and its fine particle size means it is of little benefit to soil structure, plus, it may contain toxic by-products.

[Robert_Brenchley]

Coal ash is good for paths, and little else.

[gray1720]

Thanks folks, as I'm fairly sure it's wood ash I'll buttonhole the offerer next time I see them.

Adrian

[Vinlander]

Moderation is the key.

If you are on horrible heavy clay then the potassium hydroxide in wood ash can push calcium out of the clay particles and make it more claggy than it was (by changing the electrostatic properties) - but you'd have to use a lot in one place - and in one place that didn't have a lot of humus in the soil - so if you habitually use plenty of manure/compost it's unlikely to be a problem.

Of course you shouldn't let anything alkaline like this near recently manured soil - it can release precious but unpleasant ammonia to the air - just like lime does.

Cheers.

[Digeroo]

Since it is said to be alkaline, so I avoid raspberries.  Beans seem to like it. 

I like wood ash.   I find the nutrient leach out so any thing free is great.

[Vinlander]

Of course something far better than wood ash is wood charcoal. Even partly-burned stuff is good. If your environment will tolerate the extra smoke you can damp a file like the Amazon indians used to.

It is a long-term carbon store (millennia), excellent at holding water and nutrients that would otherwise run away, encourages the micro-organism ecology and improves the structure of the soil.

Just don't buy it purpose-made from garden suppliers unless you are a millionaire - you may feel more confident that phenols and other nasties have been removed but you are paying through the nose for something that may not exist.

Certainly city garden experts will tell you that fruits or seeds are safe to eat from anything except the worst polluted land - the plant protects its offspring.

All charcoal will lose its nasties after a year in the soil anyway so don't go for roots in the first year (and avoid the oil-soaked quickstart stuff of course).

Cheers.