[Terrapreta] charcoal in agriculture

[Richard Haard]

Hi Tom

The present posting is a strictly visual comparison of Lonicera  
plants. Shortly, I will repost my chemical tests and I will be  
finished for the season.

First of all it was obvious as the lifter-shaker went through the  
plots that the single pass of rototilling did not uniformly mix the  
charcoal .  The blades seemed to throw the charcoal laid on the  
surface towards the right for the first few feet of the bed. In  
hindsight, we should have done 2 passes, forward and back. Now that  
the plants have been lifted and the plots replanted the charcoal is  
quite uniformly mixed.

Some of the roots that came out of a bed were not black stained yet  
others were.  In any case when I carried out my early fall look at the  
bed it was obvious that the fine charcoal treated plants / in  
combination with compost or compost/fertilizer looked better. After  
lifting the plants though the root systems on the broken charcoal  
treatments also looked pretty good but the fine powder was better.

Keep in mind that besides particle size they were also different  
sources. The larger size charcoal however gives me an opportunity to  
observe interaction with soil invertebrates and fungi. Also to observe  
how the charcoal is weathering, becoming water-soaked and so on.

After I made my early observations I went through all the plots with a  
trowel and dug up a core of the soil to look closely at the mix. I was  
surprised at first to seem to have more insect activity in the plots  
with no compost but spending a whole afternoon on this the trend  
disappeared. The insect I noticed is a cottony aphid that commonly  
feeds on plant roots on our farm. With one crop, serviceberry it is a  
problem where the seedling plant reacts at the  root collar forming a  
fragile parenchyma that causes the stem to break. It was interesting  
to see and to view this as a soil nitrogen reservoir. Later in winter  
we typically see masses of springtails, a saprophytic invertebrate,  
migrating to the surface. None yet on these plots. The mycelium that I  
found was associated with the sawdust used to make the compost, not  
especially with the charcoal. This is in contrast to the mushroom  
mycelium on the charcoal Larry is working with and there was also an  
absence of nematodes and segmented worms we found on his pretreated  
charcoal.  The fungus by the way is birds nest fungus (Nidularia sp.)  
and is common everywhere on the farm where we use this compost as mulch.

Nearby where Larry and I made our charcoal via buried mound, several  
pieces of charred wood laid on the surface all summer and when we  
picked them up they had mycelium of a typical mushroom type. Something  
that was lacking in the treatment beds. I am thinking that the  
charcoal in these test beds will be maturing in coming seasons ,  
perhaps as volatile matter is decomposed by microbes and the charcoal  
becomes completely water saturated.

There may very well be a kind of ecological succession from a primary  
new habitat to a climax community that occurs on each piece of  
charcoal. The smaller particles are easier to colonize. I would really  
love to pose this question to Dr Ogawa. The differences with what  
Larry accomplished and what I have observed on the charcoal pieces in  
my tests is dramatic. What I theorize is happening is the complex  
carbohydrates and urine (urea) he is applying acts as substrate for  
organisms that convert the charcoal to a habitable form quickly. On  
the other hand this process may take place over a year or 2 in my test  
plots.

For about 5 years when I was beginning to grow willows from seed at my  
farm I also studied natural recruitment of willow seedlings on a new  
gravel bar in the Sauk River. On the farm with summer irrigation,  
fertilizer and fertile soil the plants made 4 feet or more height in  
the first season. On the gravel bar they took 4 years to make 6 feet.  
On the gravel bar seedlings became established where seed floated in  
temporary rain puddles and on shallow or well drained puddles they  
died. In this case, I believe the main difference was because of our  
natural summer drought and the time it took the stressed seedlings to  
make good root systems. What Larry has done may be the equivalent and  
we need to devise a controlled experiment to test this notion.

The beauty of this charcoal treatment experiment is that I can take a  
similar span of time to see if these kinds of successional changes  
will occur. By removing all productivity from the beds I am exporting  
an unnatural amount of nutrition from the plots. This is something  
that Christoph Steiner did not do in his studies, athough the leaves  
did drop before and during harvest. In deciduous plants leaves bear  
most of the nutrients.

Rich








On Jan 7, 2008, at 8:20 PM, Tom Miles wrote:

> Richard,
>
> If you look at a slice of soil mix from each of your test conditions  
> after the growing season can you see a qualitative difference in the  
> charcoal itself, or the blend for each fraction? Does the soil in  
> the most productive mix look different than the least productive  
> mix? Do the results tell you anything about what the charcoal  
> particle size should be?
>
> Thanks for a thought provoking report.
>
> Tom
>
>
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