Current mood:

curious

The Charculture Experiment Begins
Warning! Lunacy Ahead!

I picked up a bag of 100% natural lump charcoal from Whole Foods this morning. It's a little under $1/lb. I had no intention of grilling with it -- instead, I was going to garden with it.

See, while I was in the anarchist bookstore in the Haight about a year ago with h0mee, I ran across a small article in the back of Permaculture Activist magazine, about an ancient mystery of the Amazon. When the first Spaniards who encountered the Amazon came back to Spain, they brought reports of a massive civilization, huge cities, wealthy and prosperous. Eighty years later, when the Spaniards came back to check up on this story, they found nothing but impenetrable jungle and ruins. However, modern anthropologists knew that the modern day locals periodically stumble across "sweet spots" in the Amazonian forest, where the soil is rich and black and can be farmed for twenty years without adding fertilizer, regenerating naturally. The mystery was, where did this soil come from? Most of the Amazon grows on thin yellow rocky soil.

Recently, someone put uno and dos together; the black rich soil, called "terra preta", is filled with potsherds. What's more, the blackness of it is due to massive amounts, up to 30%, of finely ground charcoal. Though long thought to be completely inert in soil, the presence of the charcoal mysteriously creates a remarkable matrix for teeming microscopic life; bacteria and fungi living among plant root hairs, interacting with the plant resins in the charcoal, fixing trace minerals from rainfall, and generally making life good for crops and themselves. It suggests that someone, thousands of years ago, spent a goodly bit of time charring (not burning) the waste from their fields, grinding it to powder somehow, and spreading it back onto the soil. The visit from the first Spaniards most likely wiped them out in a generation or two from smallpox, syphilis, and other nasties, reducing a massive civilization to a few isolated tribes.

I've been all agog ever since reading about this, and ever so curious. Reason #1: Better crops! Reason #2: Carbon sequestration! Of course, you don't get something for nothing. Charcoal making is a damn dirty nasty carcinogenic process.



Today I finally bit the bullet and decided to try and reproduce the published results of massive charcoal amendment. Is it chemically inert in soil apart from pH modification? We'll see soon enough.

Quite by lucky accident, I noticed that the neighbors threw out a soil-filled 3-ft wood planter. I enlisted h0mee to help me carry it back to the porch.

Now, to figure out how to grind the charcoal. God help me, I did the worst thing I probably could have done (at least for my household appliance that I really love) -- I tested a single small piece of charcoal in the blender. Righty-o! It turns it to powder! It also puffs out into your face and lungs when you open the top. Hello, blacklung. God help me again, I filled the blender with charcoal, added 2 cups of water, and made a "charcoal smoothie".




I dragged a big black rubber tub into the house, and poured each smoothie into it, probably about 10-15 smoothies in all, black and shiny and goopy. I then hauled the tub back outside, scooped half the soil out of the planter, and mixed it thoroughly in the tub before putting it back in the planter.

I left the rest of the soil in the planter alone, but I mulched the top of it to retain water. I will mulch the other side soon but I wanted to take pictures of the blackness of the soil with 5 lbs of powdered charcoal added. The planter had plenty of worms and insects already, I was pleased to see that. I watered it thoroughly, both sides. I added a slug barrier, and I'm still considering adding a squirrel barrier.

On each side, I have arranged seeds for three test species:

8-9 Carrots, "Romeo" -- small bulbous carrot variety
1 Tomatillo
1 Chili, Habanero

I'm starting the tomatillo and chili inside since the outside air is still cool. The carrots I'm starting directly into the soil, 3-4 seeds thinned to their final spacing, 3" apart.

I don't have any soil sensors except for a basic pH meter. So I took some readings and averaged them out.



Initial Measurements, Day 0, March 12
Non-amended soil pH: average 5.5
Charcoal amended soil pH: average 6.0