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    I am wondering if it would be possible to use ordinary barbecue charcoal, smashed up a bit and soaked in comfrey and liquid seaweed as I have no access to charcoal finings? Having read about the S American charcoal pits and the fertility of the soil there I would like to experiment on my allotment. I have been adding as much organic matter to it as I can for the last 12 years but I think it had mainly been fertilised with growmore before that and there are still areas where the soil is not hugely productive. A few years ago I inadvertantly spread a lot of horse manure contaminated with weed killer with disastrous results so that is now a nono and I cannot produce enough compost myself to cover all the beds. My local council will not supply the compost they make – no idea what they do with it but they say it has not been tested.
    Would be grateful for your thoughts on this



     Charcoal is a hot topic, simmering nicely, intimate with global warming issues! So last autumn I made three beds, two with charcoal (one on top and one with charcoal incorporated) and one bed with manure instead of charcoal.

    At first this spring there was little difference in growth but now the bed with no charcoal is looking more abundant. The charcoal beds are fine and similar in growth, but with smaller plants. It looks like the charcoal has no especial store of nutrients itself but I think it is more a long term idea, that it conserves nutrinents which may otherwise leach, though there is no particular evidence for this, more a surmise from the Terra Preta soils of the Amazon. 

    It looks to me like adding charcoal is not like adding manure and compost, it is more about soil structure, air and root development. Worth using for long term soil quality.



    I was thinking of doing the same but for a different reason. Charcoal finings are supposed to be a good slug deterrent and been meaning to give it a try for years but never been able to get the finings.



    Thanks for your most interesting replies.
    On the last BBC Gardeners World programme they showed a gadget for making your own charcoal – a sealed tin can affair to be filled with wood and placed on top of a fire. A good idea which could be quite easily diyed I think.
    Another ongoing experiment I am trying is with bails of straw, well soaked in comfrey tea, seaweed extract, some chicken manure and pee and wrapped in black plastic so that it should decompose rapidly. I intend to spread this in the autumn but should I cover it with cardboard or something to stop the nutrients from washing out or leave it uncovered?
    Has anyone any other ideas on how to introduce more humous and nutrients into poor soil?
    My allotment is on a steep Welsh hillside. We have a very high rainfall here and I think a lot of the topsoil has gradually washed down to the bottom of the plot where the most productive soil is. I am gradually terracing it currently with damaged concrete roof tiles which do not look very pretty but at least will not rot and are free from a friendly roofer.


    Alan McAteer

    Charcoal finings are a great slug deterrent and I dress the base of my young cucumber and courgette plants with it.




    Thanks Alan
    will have to find a local charcoal maker.



    Could you use coal ash or is that totally different?



    Have you considered some terracing, perhaps using old railway sleepers or dry-stone walling? the flat terraces slow down and catch the run-off of rainwater allowing the water to filter down to the roots. They also make it easier to plant beds.

    Our local electricity company last year renewed some poles and (kindly?) left the old one lying on my land. They’ll be cut to length and used as step fronts or terrace walls (2 deep) this year! it’s an ill wind…!

    There’s lots of useful stuff on YouTube about making & using charcoal. Leave the coal-ash to your local council!



    as I understand it coal dust is too acid and I guess would have tar like substances in it. ordinary wood ash is ok I believe and I have used it in small quantities.



    i second what several people have said:
    – coal ash is toxic for the garden
    – wood ash is good either in small quantities in your compost heap, or directly around fruit trees and garlic (my garlic had an instant growth spurt after i put it on). it provides a potassium boost.
    – charcoal finings DON’T add nutrients (it’s almost 100% carbon) but DO provide nooks and crannies (surface area) for soil bateria and fungi, and water regulation in soil, thus helping long-term soil health. some permaculture types swear by ‘charging’ the finings before application, by using urine or nettle/compost tea, or putting it in the compost heap instead of straight on the garden. i haven’t had time to do this yet so i’ve just been scattering it on top of my mulch.
    – you could break up ordinary charcoal to make finings, but do see if you can find some charcoal made in UK woods, as mass-produced supermarket stuff is pretty destructive to environments overseas, whereas charcoal-making is making a comeback in the UK as part of reviving woodlands here (google coppice / woodland management for your area, or a local organic/permaculture group will know where to find it), or DIY-it as someone said


    Roger Brook

    I have been making my own version of charcoal by merely dowsing the burning embers of my bonfires to get the lovely black stuff. I think it likely that charcoal initially robs the soil of nutrients but I am finding after five years of adding to my veg garden I am getting good results.
    I think there is good potential for adding charcoal to compost ingredients- recreating so to speak the ancient middens when terra preta was laid down.
    I recently posted a blog on terra preta

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