Organic Guide to Fertilizers: Biochar

On Monday, September 12th, we welcome three experts to talk about organic fertilizers. Join us in person @zilkerbotanicalgarden or join us online. Petey from Locoal Biochar @ will be sharing how his company makes biochar from diverted waste materials. 

Biochar, also known as Terra preta, is a technique of using charcoal to improve the fertility of soils. It originated in the Amazon basin at least 2500 years ago where the indigenous people of the region create charcoal, mix it with organic matter and broken pottery, and incorporate it in small plots of land from 1 - 80 hectares in size. Terra Preta, as it is known in this area of Brazil, remains highly fertile until today, even with little or no application of fertilizers. And this is in a region of the world known for its highly infertile tropical soils. Terra Preta soils are characterized by high phosphorus content reaching 200-400 mg P/kg, and higher cation exchange capacity, pH and base saturation than surrounding soils. 

In recent decades, western researchers are just starting to acknowledge the many ways that Indigenous peoples have shaped forest composition and its diversity, and domesticated native plants. In other words, the Amazon didn’t happen on its own or “naturally.”

Regions of the world devoid of organic soil carbon have very limited food chains, and little opportunity for the few human inhabitants they can support to develop beyond occupations such as goat herding. 

Modern agricultural techniques, including tilling and abundant use of chemical fertilizers, pesticides and herbicides, have caused most of the soil organic carbon in developed regions of the world to decompose to CO2. One third of the excess carbon dioxide in the atmosphere is from our soils.