Mixing Char and Bokashi


By Daniel Dalegowski

Takilma, OR, February 17 2010. Today the students did two activities in small groups. Kelpie helped the students mix charcoal with the urine they have been collecting over the last several weeks and Joe gave the kids a lesson on bokashi and compost.

While Kelpie's part of the lesson was more hands-on and exciting, Joe's part was more like a standard lecture. Since there were three groups of students participating in a rotating manner, I attended one session with Kelpie and two with Joe. You will notice this arrangement in the article below.

Mixing the Char


I accompanied the first small group that went outside with Kelpie to mix char with urine. Kelpie also brought liquefied fish guts (also known as fish emulsion) and seaweed to mix with char. Not every student had the opportunity to collect urine and in these cases the children mixed fish guts or seaweed instead.

To make a proper fish guts mixture, four tablespoons of fish guts was mixed with each gallon of water. For seaweed, two tablespoons was mixed per a gallon. The students took turns measuring fish guts and seaweed into their buckets; it was a good exercise in counting, fractions, multiplication, and dexterity. A total of three non-urine buckets were mixed.

The buckets were labeled to indicate weather they contained urine, fish guts, or seaweed.

Kelpie noted that children's urine contains more growth hormone than adult urine. This could have an effect on the growth of plants in the biochar and the class made an effort to keep track of the who contributed the urine in each bucket. In some cases the urine of only a child was collected, but often a parent contributed. The gender of the parents and students in question was also recorded.

Kelpie said that in two weeks when the buckets of biochar are opened they will smell far less than they do now. The fresh urine is generally quite smelly, but infusion into charcoal for two weeks should absorb much of the odor-causing chemicals. Charcoal is well-known for it's use as a gas- and liquid-purifier and this is the effect we should see in the biochar buckets.

At one point there was a mass-exodus from one particularly smelly bucket. A student commented "Ewww, it looks like orange juice!" and another "Anybody have a cloths-pen?"

Kelpie brought several bags of charcoal to mix with the urine, fish guts, and seaweed. The charcoal was in large chunks and it was necessary for the students to jump on the bags violently. They performed this duty admirably. As usual, a larger degree of physical interaction was required from the students, making the lesson more interesting.

Kelpie added charcoal to each bucket and mixed them in turn. Black, carbon dust was emitted during this process and the children were advised to stay a safe distance away. Breathing large amounts of charcoal dust can harm the lungs and this part of the activity was performed by responsible adults.

It's a good idea to crush the biochar further after the initial two weeks of soaking has passed. One technique is to put it through a leaf-shredder, which is what we will be doing most likely. In the absence of such a machine, biochar can be wrapped in a tarp and driven over repeatedly with a car to break up the large chunks.

I accompanied the group as they went inside to join Joe for a lecture on bokashi and compost.

Bokashi and Compost


1st Session with Joe


Joe opened the lesson with a discussion of compost. He asked what it is, which the students seemed to have a clear grip on already--many have experience gardening at home. Joe asked what can be composted. One student answered "barf!" Joe confirmed "yes, you can compost barf." Another student offered "fish guts!" It was difficult to calm down after the physical activity outside.

Joe and the kids discussed what was in a compost pile. Worms, grey stuff, food, and mold came up. The students confirmed that dogs were commonly found in compost piles, eating the food, but the point was made that generally worms, fungus, and rodents consume compost.

Joe took the students outside to the Dome School greenhouse. He showed them some compost that he had collected and arranged for the lesson. Joe pointed out worms, charcoal, poop, pee, and other substances that were in the compost and explained the role worms play in eating all the different materials.

Back inside Joe showed the students a bucket of bokashi he had brought and had them smell it. The smell was mild, like a mix of compost and kimchee or sour kraut. Joe brainstormed with the students about what animals and other organisms would be found in compost and the students drew pictures of several of these.

2nd Session with Joe


Joe quizzed the kids about how old they were and which ones had a garden at home. Some of the students have to take out the compost as one of their chores. There was consensus that compost generally smells bad and one student noted that it tends to have lots of banana peels in it.

Joe asked the students to define bio-degradable. One answer given was that something is bio-degradable if it "turns back into the earth." Joe liked that answer and asked the students to think of things that are not bio-degradable. Answers included glass, metal, rubber, and gold. Joe remarked that rubber could be bio-degradable, but it was a good answer.

Next, Joe wanted to know what animals would be found in compost. Answers included worms, potato bugs, and millipedes. Joe added that bacteria are perhaps the most important critter living in compost. One of the students said that "bacteria are little animals that eat things." Joe added that yeast are also found in compost piles. When one makes bread the yeast release tiny bubbles that cause the bread to rise. The same is true for a compost pile; a lot of gas is produced as bacteria and yeast break down the vegetable matter and other waste into soil.

Joe did a brief review of the previous, outside session in which the buckets of char were mixed. He then asked the kids if they liked sour-kraut or kimchee to which they answered "Yes!" Joe explained that bacteria and yeast make cabbage into sour-kraut and kimchee. Then Joe showed the kids the Bokashi. It smells a little like sour-dough bread because it's filled with bacteria and yeast designed to add to a compost pile.

We then examined the worms in the green house and Joe explained about the fresh horse poop, biochar, tomato skins, and shredded paper that the worms were eating. Worms love shredded paper. When Joe added biochar to the worm-food mixture, the worms went for it with gusto; biochar was a big hit with the worm community. Joe explained that the worms were eating the poop. A student asked if worms would eat human poop, to which Joe answered "they'll eat anything!" "What about people?" a student asked. "If you're dead under the ground they'll eat you" Joe answered. "Ewwww!"

Back inside Joe asked the kids what they might put in compost. The main answers were food and poop. A student asked why it was bad to add human poop to compost. Joe answered that disease can be easily transfered that way.

Joe asked the kids to speculate on the role of mushrooms in compost. He explained that mushrooms send out their mycelium into the compost pile, like the roots of a tree spreading through the earth, and the mycelium decomposes and extracts nutrients from the compost pile. Then it makes mushrooms on the surface that slugs and snails generally eat, but sometimes humans and other animals can too.

Joe asked what animals eat dog poop? The obvious answers was "dogs" of course. Joe agreed, but often, and less obviously, snails and slugs eat most of the dog poop that's around. The students then discussed who held the world record for the most slugs on his or her face.

The group that had been outside returned and the students started to rearrange the room for lunch.