[Terrapreta] Fwd: compost and charcoal

[Kevin Chisholm]

Dear Michael

Michael Bailes wrote:
>
>     *A.   What materials should not be composted? *
>     Most ashes are safe to mix into your compost heap, but coal ashes
>     are not. They have excessive amounts of both sulfur and iron,
>     amounts that are toxic to plants.
>
>
> Do you think Gerrit that this would apply to all coals from all areas?
> I am especially thinking of Victorian Brown Coal which just seems a 
> few steps up from compost and peat and contains 7 holds a great deal 
> of water.
> It my be that it might form a carbon-rich soil amendment on its own.(?)
You raise a very good point. Firstly, it is wrong to say that "most 
ashes are safe" without specifying the quantity. Some wood ashes are 
safe, when growing some crops, when added up to a particular maximum 
level. The amount of "clean" wood ash that can be added with benefit and 
no detriment to a crop of blueberries or rhododendrons is a lot less 
than  can be added to a crop of beans. On the other hand, wood ash from  
demolition of old buildings containing lead based paint, or from the  
disposal of CCA treated wood may be toxic at very low levels.

Iron and sulfur are usually only "bad" under coinditions of low pH. On 
the other hand, if adequate lime was added with the coal ash, the 
acidifying characteristics of coal ash could be neutralized, so that 
there was no detrimental effects to plant health even with relatively 
large levels of addition. Additionally, high levels of "acidic" coal ash 
could be remarkably beneficial to Dr. Reddy's work treating alkaline soils.

While Gerrit was quoting someone in reference to coal ASH, you seem to 
be referring to additions of unburned brown coal. The unburned brown 
coal could be an excellent soil addition for the same reasons and under 
the same circumstances where biomass charcoal was beneficial. Indeed, 
there may already be a commercially proven confirmation of your idea... 
I understand that Leland "Tom" Taylor is associated with a company that 
sells a mined soil amendment that might be close to your brown coal 
concept. Indeed, Victorian Brown Coal, and Leland's product may be an 
excellent source of trace elements and micronutrients.

Best wishes,

Kevin