Simon Kitol’s 25-hectare farm in western Kenya teems with maize, tomatoes and beans, but also an invasive threat: Prosopis juliflora, better known as the mathhenge plant. Its long roots steal water from its crops, and the shrub takes up valuable space to grow food. Kitol’s livestock also feed on the mathenge pods, which are loaded with sugar, causing even more problems.
“It damages their teeth, and eventually the cows or goats die,” Kitol said. The thickets also provide cover for predators such as wild dogs and hyenas. “They hide there because it’s so thick you can’t see them. At night, when the goats or sheep roam, they are attacked and killed.”
Last year, experts with Penn State’s PlantVillage project, which helps small farmers adapt to climate change, arrived to train Kitol and others in the area on a clever way to turn mathhenge from a problem into an asset. Workers collect those pesky weeds – biomass – and turn them into biochar, concentrated carbon that they “load” with nutrients by mixing it with manure. Farmers then apply the mixture to their fields and sometimes plant grass that provides fodder for livestock. Kitol said the biochar helps his soil retain water and improve their fertility, leading to higher yields.
Far beyond Kenya, biochar is having a moment: The global market was worth $600 million last yearand could rise to more than $3 billion next year. Wherever people produce waste biomass—corn stalks, weeds, dead trees—they also produce a powerful tool for sequestering carbon and improving soil. And if farmers can prove how much biomass they turn into biochar, they can prove how much carbon they put back into the soil. Through a group like PlantVillage, a company can then pay those farmers to offset its carbon emissions. (Biochar is generally more than 90 percent of durable carbon credits which has already been delivered worldwide.)
With biochar, farmers therefore get a new source of income and a way to better retain rainwater and increase yields. They help mitigate climate change while adapting to its devastation. “To help solve a problem with invasive species and land degradation, and produce biochar at the same time, is amazing,” said James Gerber, a data scientist who studies agriculture at the nonprofit climate group Project Drawdown. “Anything that gets money into the hands of small farmers in Africa is probably only a good thing. But if it’s part of a functional, verifiable carbon credit program, even better.”
The trick to making biochar is pyrolysis. As people knew for millennia, if you expose biomass to very high temperatures, but in a low oxygen environment, it does not burn in all-consuming flames; it turns into a kind of charcoal. Companies can do this with large industrial chambers, which produce the biochar that you can buy for your garden. Small farmers can do this by digging a pit and adding biomass in layers, which restricts oxygen to the smoldering fire at the bottom. A simple kind of metal oven do the same.
Whatever the method, the plant material is not all burning and billowing smoke. With biochar, you end up with concentrated, solid carbon. “It’s essentially coal,” says David Hughes, founder of PlantVillage. “It goes into the soil and it doesn’t break down, and that’s because of the temperature you expose it to.”
Because biochar is so spongy, it helps the soil retain more water—a particularly welcome feature given the worsening droughts in Africa and elsewhere. But that sponginess also requires special care when applied to a field. “If you just put biochar in the soil, it will soak up all the nutrients in it, and your plants will do worse,” Hughes said. “So you have to load it with nutrients. You can do this with compost or NPK – nitrogen, phosphorus, potassium – mixtures.”
Traditionally, a farmer might burn piles of waste such as corn stalks, releasing carbon into the atmosphere. If different farms across a landscape do this after a harvest, air quality drops and endanger human health.
So for a group like Biochar Life, which provides carbon removal offsets for biochar, the first step is to get a farmer to stop processing their waste biomass the old way. “We have to prove that the farmer didn’t burn it or just leave it there and let the biomass decompose and create methane,” says Aom Kwanpiromtara Suksri, the co-founder and global head of development and compliance at Biochar Life, which has offices in Asia and Africa and has formed a partnership with PlantVillage.
To be sure, carbon offset systems have been plagued with problems. One is a perverse incentive to deforest an area and replant trees and sell those credits to companies. Where there has been deforestation from logging or agriculture, planting a clump of a single tree species does not create a proper ecosystem. There is no boost to biodiversity, and tree plantations do not sequester nearly as much carbon as a real forest.
By contrast, Biochar Life says its settlement system is easier to quantify, and that so far it has distributed more than $300,000 to farmers and $265,000 to local teams that verify the credits. “We cannot generate a credit until we have proven that we have generated biochar, and that biochar has been loaded and put back into the ground,” says Matt Rickard, Biochar Life’s chief operating officer.
Then there’s the issue of permanence: If farmers plant a bunch of trees and a drought hits, and those trees all wither or catch fire, their carbon goes right back into the atmosphere. Scientists are still working out how long biochar can last in different types of soils and climates, but indications are that it can thousands or possibly millions of years. And compared to waiting for a tree to grow and capture carbon, adding biochar to soil sequesters the carbon immediately in the soil.
“Biochar, it’s kind of chemically locked in — it would be very difficult to reverse that,” Gerber said. “To me, this is the main reason why biochar has greater potential for carbon credits.”
And unlike planting a new forest and walking away, farmers can continue to produce biomass, replenishing it with nutrients and adding it to the soil year after year. At the very least, a small farmer like Kitol gets a better handle on an invasive species while increasing yields and preparing his land for the drier times ahead. “I see the future of biochar as promising,” Kitol said. “Biochar will be widely used as more people recognize its benefits.”
