[Terrapreta] cover cropping as a charcoal in soil evaluation.

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Terrapreta reading listers

 

My introduction to using charcoal in soil for agricultural purposes came in
2004 <http://www.georgiaitp.org/carbon/carbonconf.htm>  at the conference
held at University of Georgia. Returning and very enthused to give it a try
I set up some experiments using purchased lump charcoal and inoculation of
red alder with Frankia, a root nodule, nitrogen fixing organism. 

 

That winter, 2004-5 I met by way of conversations on line with the
gasification list, John Flottvik and learned about his work with a pilot
plant pyrolyser. At the time he was working less than an hour drive from our
farm just across the border in British  Columbia. John graciously offered to
donate a tote of charcoal powder for my research program.

 

Finally, John here are some results from that work. !!

 

At the time three of our adjacent fields were fallow and we were cover
cropping with gray oats beginning in early fall. We grow in these fields
native plants in small blocks. Sometimes as many as 100 species of plants.
It was interesting to note that mineral uptake by the different crops showed
in the cover crop then uniformly planted on the field. Here
<http://www.flickr.com/photos/rchaard/396830233/sizes/o/in/set-7215759444499
4347/>  is an image of that gray oats cover crop taken fall 2004. Note that
on the far left the cover crop had already been worked down and on the right
the field had heeled in stock. In the foreground a general mottled growth in
the gray oats can be seen from differing fertility. 

 

Wouldn't it be interesting then to treat several bands of these fields with
this charcoal powder, crop the field for 2 years and then use a later cover
crop planting to determine if the charcoal was having an effect on the soil
fertility. We then worked in the gray oats and treated two bands of 6
seedbeds (each seedbed is 50 inches by 500 feet.) with aisles for tractor
wheels, making 8 feet. The charcoal powder was mixed with commercial compost
and applied to each seed bed strip with a manure spreader. We never did have
a weight of the charcoal in the tote but I estimate we put 100 lbs of
charcoal on each strip. Quite a bit of it as you can see in these images
went airborne but the soil surface wound up black in the right places. Here
<http://www.flickr.com/photos/rchaard/396838824/in/set-72157594444994347/> ,
here
<http://www.flickr.com/photos/rchaard/396838820/in/set-72157594444994347/>
and here
<http://www.flickr.com/photos/rchaard/336687415/in/set-72157594444994347/>
are several images to show what we did at that time is our charcoal
application

 

The untreated beds were given compost without charcoal powder and the entire
field received a single treatment of  commercial fertilizer, a 5 - 10 -10
with micronutrients , a formulation we are no longer using.  After planting,
a light application of urea was used in late June when the seedlings were
well established. Typically on our farm, a bare root nursery, we harvest
parts of each field and leave the rest for harvest in second year. The blank
spots in the field are usually filled in with transplants and our normal
cycle of cropping any field is then completed in 2 growing seasons. Worst
case happened though for this charcoal experiment as we were not able to
clear the entire 3 fields and reestablish cover crop because we needed the
production space and replanted without fallowing. 

 

We were able to cover crop one side of field 3 that had 2 rows treated with
charcoal powder and the remainder untreated. My cover crop this spring was
an early planting of mustard (Brassica). We planted the mustard in March and
have just worked it in on June 12. The results are most encouraging to me
but because we were not able to treat the entire 3 fields in this way will
have to wait for more conclusive observations and soil testing.  These
<http://www.flickr.com/photos/rchaard/2579959420/?addedcomment=1#comment7215
7605621598529>  pictures show very distinct differences in growth of the
mustard cover crop that received charcoal powder versus untreated. As we are
replanting the entire set of fields spring 2009 then the next opportunity to
view this cover crop effect will be 2011 or 12. 

 

My conclusion is that we need to be conducting long term evaluation of
charcoal effects in soil. This cover crop method may be the best way to show
beneficial effects. Our soil management methods are pretty much mainstream
in that we use commercial fertilizer and urea. Here is an indication that
the use of charcoal has a positive effect on soil fertility and that the use
of charcoal may reduce the need for fertilizer applications at our present
usage rates. 

 

Rich Haard, Fourth Corner Nurseries, Bellingham, Washington

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