admin | December 18, 2024
News Brief
In western Kenya, Simon Kitol has turned the invasive Prosopis juliflora plant, or mathenge, into an asset. Previously a nuisance, the plant’s biomass is now converted into biochar, which improves soil fertility, water retention, and yields on his farm. He says, "I see the future of biochar as promising." Biochar, a carbon-rich substance, is gaining popularity worldwide for its role in improving soil health and generating carbon credits, offering farmers new income opportunities.
Simon Kitol’s 25-acre farm in western Kenya teems with maize, tomatoes, and beans, but also an invasive menace: Prosopis juliflora, better known as the mathenge plant. Its long roots steal water from his crops, and the shrub takes up valuable room for growing food. Mr. Kitol’s livestock also dine on the mathenge pods, which are loaded with sugar, causing even more problems.
He explains, “It damages their teeth, and eventually the cows or goats die.” The thickets also provide cover for predators like wild dogs and hyenas. He adds, “They hide there because it is so thick that you can’t see them. At night, when the goats or sheep walk around, they are attacked and killed.”
Last year, Mr. Kitol participated in a training on a clever way to turn mathenge from a problem into an asset. This training was offered by Penn State’s PlantVillage project. Farmers were encouraged to gather up those troublesome weeds — biomass — and convert it into biochar, concentrated carbon that they “charge” with nutrients by mixing it with manure. Farmers then apply the mixture to their fields. Mr. Kitol said that the biochar helps his soils retain water and improves their fertility, leading to higher yields.
Biochar is increasing in popularity in many places around the world. Last year, the worldwide market was worth $600 million US and it could rise to over $3 billion next year. Anywhere people are producing waste biomass — corn stalks, weeds, dead trees — they’re also producing a powerful tool for sequestering carbon and improving soils. And if farmers can prove how much biomass they’re turning into biochar, they can prove how much carbon they’re putting back into the ground.
Through a group like PlantVillage, a company can then pay those farmers to offset its carbon emissions. Biochar in general accounts for over 90% of durable carbon credits that have already been delivered worldwide.
So with biochar, farmers are getting a new source of income and a way to better retain rainwater and boost yields. They’re helping mitigate climate change while adapting to it.
The trick to making biochar is pyrolysis. As people have known for millennia, if you expose biomass — or renewable organic materials from plants and animals — to very high temperatures but in a low oxygen environment, it doesn’t combust into all-consuming flames; it turns into a kind of charcoal. Companies can do this with big industrial chambers, producing the biochar that can be sold at market. Small-scale farmers can produce biochar by digging a pit and adding biomass in layers, which restricts oxygen to the smoldering fire at the bottom. A simple kind of metal kiln does the same.
Whatever the method, the plant material isn’t fully combusting and billowing smoke. With biochar, you end up with concentrated, solid carbon. David Hughes, the founder of PlantVillage, explains that biochar is essentially coal. He adds, “It goes into the ground and it doesn’t break down, and this is because of the temperature you’ve exposed it to.”
Because biochar is so spongy, it helps the soil retain more water — an especially welcome trait given the worsening droughts in Africa and elsewhere. But that sponginess also demands special care when applying to a field. Mr. Hughes explains, “If you just put biochar into the soil, it will suck up all the nutrients in there, and your plants will do worse. So you have to charge it with nutrients. You can do that with compost or NPK — nitrogen, phosphorus, potassium — blends.”
This can be done by mixing biochar to your composted manure pit to help mature the compost while it activates. Farmers can mix biochar into the compost up to an equal ratio of each. Ensure the biochar is wet before added. Allow the biochar to mix with composted manure for several weeks.
Biochar can have long-term benefits for the soil, and farmers can keep producing it from plant waste, charged with nutrients from the compost pit. Additionally, farmers like Mr. Kitol are turing an invasive species into an asset that will help him adapt to climate change. He says, “I see the future of biochar as promising. Biochar will be widely used as more people recognize its benefits.”
This story was written by Matt Simon for Grist and published with the title “This simple farming technique can capture carbon for thousands of years.” Read the full story: https://grist.org/climate/biochar-farming-capture-carbon-thousands-of-years/
Photo: Simon Kitol on his farm in Kenya. PlantVillage