[Terrapreta] Char application negative / delayed benefits

[folke Günther]

I addressed this problem in an article written last year:*
* **

*"However, if you add a lot of fresh charcoal to the soil, the previously
existing fertility might temporarily decrease. This, and the length in time
of this phase, depends of the properties of the charcoal. Its large inner
surface make a lot of nutrients and other soil substances adhere to it,
making them temporarily unavailable for the plants until the charcoal is
saturated. Contrariwise, when the inner area of the charcoal is full of
nutrients and soil micro-organisms, it will work as a sponge for nutrients,
readily available to interact with the plant roots, keeping the nutrients
away from leakage. *

*Therefore, the inner surface of the charcoal should be saturated with
nutrients before or during its addition to the soil. This can be done by
mixing the charcoal with compost, manure, urine, or nitrogen fixed by
Leguminous plants before or during the addition to the soil[i] <#_edn1>.
This was done by the pre-Columbian Indians when the original Terra Preta
soils were created. For the sake of differing from the freshly made
('active') charcoal, I call this nutrient saturated charcoal 'charged', i.e.
charged with nutrients. *

*In human settlements, the sewage system has been a problem since the start
of urbanisation, and an increasing group of people work at replacing the
present system with source separating toilets, producing urine and faeces in
separate flows. The problem with this, however, is that the collected urine
is highly volatile, and therefore, there are problems associated with its
long-term storage before returning the nutrients to the fields. However, if
the urine is used to 'saturate' the charcoal before it is fed to the soil,
the problems with unstable urine and the problems emanating from the fresh
charcoal might be alleviated simultaneously! "*

Simply: When you have poor soil and add charcoal, the char will adsorb
nutrients from the soil, thus decreasing its previously low nutrient status.
In a good soil, this effects will not be so dramatic. Pre-charging the char
with nutrients will avoid this problem.

FG
**
**
2008/6/5 Rex Manderson <Rexm at chaotech.com.au>:

>  Hello all – please find below a couple of delayed responses to earlier
> posts.
>
>
>
>    1. following from Michael Bailes on 1st June.  I am reluctant to talk
>    about negative effects of char application, but can identify two
>    circumstances where the outcomes were initially negative,  In a small pot
>    trial we conducted with radish and "poor" soil the char amended pots with no
>    added nutrient were 32% less biomass than the control soil sample.  In
>    contrast the char + nutrient pots were 42% more than the soil + nutrient
>    counterpart. ( hoop pine sawdust char peak 450deg 80% carbon )
>
> Rank Table:  Soil + Char   68% mass
>
>                   Soil control   100%
>
>                   Soil + fertilizer 138%
>
>       Soil + char + fertilizer  196%   ( expressed as 196/138= 1.42 for 42%
> )
>
> From this we concluded simply that if there is not enough nutrient to
> satisfy all the life in the pot, then the microflora will win the race for
> the available nutrient.
>
>
>
> I have also had discussion with some other experimenters who admitted to
> knowledge of negative results, which may have come from the presence of a
> large amount of unconverted material since the char in question had a low
> carbon content.
>
>
>
> In summary lousy soil or lousy char can both result in nothing gained.
>
>
>
> 2.  following from Greg H on 5th June
>
> "and then trying to convince farmers to spend the money on something that
> is not going to return any benefits for at least the first couple of years.
>
>
>
> Greg H."
>
>
>
> In that same pot trial the char was added the day of planting and the
> radish harvested 30 days later.  There was absolutely no waiting for the
> benefit to be realized!   I can imagine circumstances of application where
> the results do not appear for some time, and could probably find references
> for published work with this profile.  However this is not a proof that
> delay in benefit is an inevitable part of the char process.  We just need to
> use good stuff with appropriate attention to the condition of the soil to
> get an immediate gain.
>
>
>
>
>
> If anyone wonders why this little 10 pot trial is not in some data base or
> published, I have to say that without some attempt to characterise the char
> and the soil it is all just a collection of anecdotes.
>
>
>
> I hope to be able to provide more useful data in future, but we have had
> our next set of pot trials on hold since January because I have not invested
> the time to find a source for a reasonable fertiliser application schedule
> to use in the series.  We do not appear to have attracted too many
> commercial farmers to this list, and perhaps that is something that some
> contributors should take as an indication of poor input.
>
>
>
> Regards,
>
> Rex Manderson
>
>
>
>
>
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>



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