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Biochar Coffee Tests Show Improved Yields, Quality and Soil Health

Biochar application in Tanzania. All photos courtesy of Radio Lifeline.

The U.S.-based nonprofit Radio Lifeline has already received astounding data related to yield increases when biochar is applied to mature coffee plants. Now the group has identified more data showing positive associations between the application of biochar and other important factors such as coffee quality and soil health.

What is biochar? In short, it’s a highly porous form of charcoal, which in this case is produced at origin in cost-effective (approximately $40 USD) repurposed drum kilns using any biomass that might happen to be laying around, such as corn husks, twigs or cow dung.

Increased Yields

The Radio Lifeline-led Black Earth Project has been testing the efficacy of biochar as a soil amendment to coffee plants to potentially increase yields, improve soil health both in the short- and long-terms, and increase coffee quality. After some funding from Keurig Green Mountain, biochar produced remarkable results during tests concluded in 2015 in Rwanda. Earlier this year, based on tests in Tanzania with funding provided by the German Development Bank (DEG) as part of its Coffee Partnership of Tanzania, biochar was shown to dramatically increase yields.

Of course, sustainable production requires more than merely increased yields, and now Radio Lifeline has received reports from project partners in Tanzania regarding cup quality and soil analysis.

It should be noted that the project was conducted over one particularly rainy season involving six test plots, meaning the data is limited and more testing would be required in order to make any sweeping generalizations about the efficacy of biochar in coffee. However, the limited data that exists provides fertile ground for optimism.

Quality in Tanzania

A new report from Black Earth Tanzania project partner Tembo Coffee Company, based in Mbeya, suggests plots treated with biochar displayed superior quality attributes to those that were not, while even demonstrating characteristics not typically found in the region.

“We can see that the coffee coming from trees with biochar application is in general giving better results in term of defects count, screen sizes and even in the cup. The tea-like and floral profile is not very common in the region and makes this coffee special and more complex,” Tembo’s Line Cosmidis said in the report. “Having a better parchment to green yield and a better first-grades yield is really important for the farmers because this is a crucial criteria for coffee buyers like Tembo Coffee to agree on a final price as buying the coffee from them. Tembo Coffee also takes into account quality (cupping results) as fixing a price with the producers.”

Using the SCA scoring system, Tembo found that the coffees treated with biochar on average scored two points higher (83) than those that were not (81).

Soil Health

Soil analysis for a seven-month period beginning in January 2017 showed similarly promising results. The Tembo report says biochar-treated soils showed an increase in essential elements over non-biochar-treated soils, with a slight reduction in calcium levels being the exception; the biochar-treated soils had little effect on soil pH; and biochar-treated soils demonstrated increased moisture retention (53 percent) and dramatically increased cation exchange capacity (98 percent), which influences soil’s ability to retain essential nutrients.

Graphic courtesy of Radio Lifeline.

“With mounting evidence pointing to the need for new economic models and an increase in sustainable practices to ensure the future of coffee farming, biochar could provide a valuable tool to smallholder farmers trying to meet the mounting challenges of climate change, increased input costs, lower yields and decreasing soil fertility,” Radio Lifeline said in a reaction to the Tembo report. “Biochar amendments present farmers with the possibility of engaging in farming practices that can actually help to regenerate soil fertility instead of just trying to preserve a slippery slope of the status quo.”


1 Comment


Hi, Thank you very much for carried out outstanding work on biochar to increase yield of coffee. It is fact that biochar alone not give more response compared to biochar + chemical fertilizer or compost.

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