Questions on using wood ash to lime a plot

[Dave & Kate N Wales]

Hiya,
I read that you can use wood ash to lime your legume patch, but I have some queries if anyone can help.
When? Should this be done. Is it too late now we'll soon be planting up.
How much? Per square meter say?
And most importantly, my friend with a wood burning fire, against my strong advice, burns pressure treated and varnished wood. Will there be poisons in the ash as in the smoke?

Thanks in advance for any help and advice
Dave

[solway cropper]

Not sure what you mean here. Surely you can only lime a plot with.....lime!!

Wood ash contains decent amounts of potassium which is why it is used as a fertilizer. It also contains calcium carbonate which is probably where you got the idea from. So yes, you could use it to sweeten an acid soil but I'd be inclined not to use ash from treated timber as you never know what you're putting on your soil.

As an aside, a recent study has shown that bumper crops can be achieved by mixing wood ash and human urine to use as a fertilizer.

[TallGirl]

Excellent, I was looking for info on this. I've been saving wood ash to 'lime' the brassica bed, with the hope that because it's so alkaline it'll reduce the acidity of the bed in the same way as lime would. But I didn't know if it was actually a sensible thing to do or not.

Off to pee on the compost bin...

[taff]

It more usually used on fruiting stuff thanks to the potash it contains. The nutrients wash away quickly in the rain too.