[Terrapreta] Life cycle of forest fire char?

[Green Waste Recycle Yard]

I was trying to explain pyrolysis yesterday to some well-meaning old school
environmentalists who have the classic anti-burning bias. I was trying to
explain the difference between black carbon and carbon in compost/mulch, and
that the BC was basically unavailable as a direct plant nutrient, that its
function in Terra Preta is not as a nutrient, and that it could last for
hundreds of years without degradation. They had a hard time wrapping their
heads around the idea of low degradation soil-sequestered char, stuck in
their idea that the best use for green waste MUST be compost or mulch.
 
As their counterargument, they said that all the char from a forest fire was
essentially gone a few years later, therefore (in their view) it must have
been biodegraded as a nutrient. If true (that it is gone), I suggested that
most of it was removed by water run-off, but I actually don't know. So I'm
asking here. What happens to char produced by a forest fire?
 
1) Is it mostly not pure charcoal, and thus does get utilized as a nutrient?
2) Does it wash/blow away because it is on the surface?
3) Does it enter into the soil?
4) Does it actually "go away" as they claimed? Or is this just simplistic
observation on their part?
5) Some combination of the above, or other explanation?
 
No need to go into a detailed response if you can simply point me to
appropriate articles, etc instead.
 
There is going to be a lot of resistance from old school anti-burners, so it
is important to know how to answer their questions and help them reframe
their thinking.
 
TIA,
Bernie
 
 
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