Location: Hawaiian Mahogany Farm Lawai on the island of Kauai in Hawai’i
Featuring: Jeff Wallin and Josiah Hunt
Black is the new green.
Biochar: a sustainably made charcoal substance that increases soil fertility (and sequesters carbon)
Five properties that make biochar valuable in agriculture:
1. A biochar partivle is porous; its high surface area allows it to capture and retain many times its weight in water.
2. It increases nutrient efficiency by attracting cations (positively charged ions, which include plant nutrients like calcium, magnesium and potassium) and anions (negatively charged ion, which include nitrates and phosphates), sharing them with the soil food web.
3. Biochar is resistant to biological and environmental decay. It can last in the soil for hundreds to thousands of years, making it an effective form of carbon sequestration.
4. Provides a secure habitat for fungi, bacteria and other microorganisms.
5. It enhances soil aeration.
How to make biochar:
1. Fast growing Albizia Trees are cut down
2. A chipper turns the timber into wood ships
3. The wood chips are shoveled into a feed conveyor
4. The conveyor maintains a constant flow of chips into the kiln
5. A kiln converts the wood chips into biochar via the process of pyrolysis [from the Greek: pyro (fire) + lysis (separatint)]. The combination of intense heat + limited oxygen makes it possible to convert organic carbon (wood) into stable carbon (biochar)
6. Steaming hot char travels out of the kiln and drops into a wheelbarrow
7. The biochar is now ready for agricultural use, either by adding it directly to the soil or mixing it with additional soil amendments.
Location: Josiah’s Front Yard in Pahoa, Hawaii
The Biocharista: Someone who specializes in the art and science of blending biochar
Josiah transforms scrap lumber from a local saw mill into a powerful soil amendment inspired by "terra preta," a rich soil found in the Amazon basin. He says: “The wood becomes black after a few hours. Instead of quenching it with water and harvesting it, I allow it to bake under the soil for 3 to 5 days at high temperature. As the embers slowly breathe through the porous soil, the biochar’s molecular structure is further refined, like grape juice becoming fine wine.”
Biochar improves soils by providing habitat for microbial life. It retains water, and sequesters carbon, making it a promising tool for climate mitigation.
How to make “Hawaiian-style Open Biochar Pit”
1. Dig a pit where large fires can be made
2. Start a fire in the bottom of the pit
3. Feed it as fast a possible while still maintaining a clean (virtually smoke free) fire. Be sure to use larger pieces of wood first, as they will take longer to burn
4. When all the wood has turned to char, cover with dirt for a few days, then moisten and remove.
BE CAREFUL! Biochar fires can burn for weeks.