[Terrapreta] charcoal experiment 4/6/8

[Richard Haard]

TP reading list

I spent some time today looking at the status of my charcoal  
treatments block study and its permutations with fertilizer, compost  
and controls. We are now in the second season growing crops on these  
plots and I expect to conduct this study for an additional 2 years at  
least without further treatment other than a possible application of  
urea applied during the growing season as is our practice at this  
nursery. I will be conducting a complete soil analysis twice this  
season again and after the May analysis data is in I will decide if  
indeed a urea treatment is needed.

When we harvested last fall the blocks were  direct seeded with a  
native shrub, Oemleria cerasiformis  or Indian Plum. Using a single  
species from one end of the experimental beds to  the other will make  
reading of the results easier. As our nursery propagates native plants  
for restoration purposes I chose this indigenous shrub because it is  
an  ecological indicator species for nitrogen rich soils. What  
interests me most in this study is the fate of organic matter and soil  
nitrogen in this sandy loam soil. Unfortunately my soil testing  
service only looks at nitrate nitrogen and any nitrogen tied up in  
soil biota as protein is not detected. Last fall soil nitrate was  
essentially 0 but the soil was teeming with biomass. This spring the  
analysis results will be interesting from this aspect and also to  
compare soil OM to project startup last year.

When the seed went down I was having difficulties with the seeding  
machine and it went down uneven. Too thick in some places and absent  
or uneven in others. Next weekend we will be thinning and moving  
seedlings to make the beds more uniform.

Here are a few images I took today, April 6, 2008. Early spring in the  
Pacific Northwest of USA.

Overview of plots, taken with telephoto and they look compressed.  
Stake spacing on plot stakes is 17 feet.

Here are Indian plum seedlings and weeds in our plot with lumpy  
charcoal. Note that some of the larger pieces tended to float to the  
surface. There was plenty of smaller size however when applied, shown  
here at time of treatment setup.

Hereis the charcoal powder treatment set in contrast to above. Small  
pieces of charcoal can be detected on surface and the soil is  
noticeably darker.

Here is a close picture of charcoal lumps that appear to be breaking  
up with natural weathering on the surface. I have also noticed this in  
timber slash burn piles 2-3 years old shown here and am wondering if  
this is because of frost action. I wondering if any list members who  
have observed charcoal in the tropics have noticed this kind of  
weathering?

Best wishes

Rich Haard, Bellingham, Washington
-------------- next part --------------
An HTML attachment was scrubbed...
URL: /attachments/20080406/8e2def80/attachment.html