Could biochar be the next important ingredient in regenerative agriculture? Wineries and grape growers in California are starting to learn about the possibilities of this ancient and vital technique for cultivating healthy soils.
A new word to describe fine-grained charcoal made from biomass sources, biochar is high in organic carbon whose primary purpose is soil enhancement. It’s also a helpful tool in combatting climate change.
“Biochar is a key ingredient in a new carbon-negative strategy that offers solutions to several critical current ecological, energy and economic challenges,” says Baltar. “It isn’t a fertilizer or food source for plants or microbes. Biochar’s use in soil is new, exciting and not fully understood yet.”
To create biochar, waste from agriculture and forestry, like vine cuttings or felled trees, are burned under intense heat that is managed in such a way as to maximize their carbon and convert the materials into as pure a form as possible.
“One of the many ways we are building our soil health is by integrating the application of biochar into our vineyard management program,” says Tony Chapman, the director of winemaking for Donum Estate in Sonoma. “Biochar is an incredible, stable form of carbon that we make from materials collected from our own olive tree prunings, vine prunings and tree debris.”
After the burning process, the material cools and is mixed into Donum’s compost. Then it’s applied to the vineyard.
“Because biochar is highly porous, lightweight and has a large surface area, it has shown to increase water retention, enhance the soil structure, improve porosity and microbial properties,” Chapman adds. “Carbon that the grapevines have fixed from the atmosphere for photosynthesis is removed from the carbon cycle and is banked in the soil through the biochar and other organic matter.”
Donum transitioned to organic farming in 2019 and will receive California Certified Organic Farmers (CCOF) certification this year. In addition, they have adopted the core principles of regenerative farming, including livestock integration and composting, as well as biochar.
There are both high-tech and low-tech ways to create biochar, but ultimately the goal is to burn hot and to reduce smoke, preserving the material as solid carbon rather than letting it escape into the air as smoke.
“Biochar is the byproduct when biomass is burned or heated with a minimum or absence of oxygen,” explains Baltar. “Recently, archeologists discovered indigenous tribes in the Amazon rainforest used char to enrich soil 500 to 4,000 years ago. Japanese used char in soil for centuries before it was replaced recently by industrial chemicals and methods.”
“Biochar is a key ingredient in a new carbon-negative strategy.”— Raymond Balter, director, Sonoma Biochar Initiative
While an ancient technique for boosting soil health, biochar was included for the first time as a promising negative emission technology in a 2018 special report by the United Nations Intergovernmental Panel on Climate Change (IPCC).
“To keep global temperatures in the range that has sustained civilization during the past millennia (1.5 degrees C threshold), the carbon balance between emissions to the atmosphere and carbon accumulation in the terrestrial system has to return to an equilibrium by 2050 at the latest,” writes Schmidt. “To achieve this, greenhouse gas emissions need to be reduced by at least 90% with the world economy becoming climate neutral by 2050.”
The 2022 IPCC special report reiterated this point, naming biochar as one of the three lowest-cost methods of large-scale atmospheric carbon dioxide removal, along with reforestation and sequestration.
“I love biochar,” says Graeme MacDonald of MacDonald Vineyards in Napa Valley’s Oakville. “The Native Americans did a lot of controlled burning throughout the valleys, which contributed to the generations of fertility. I’ve enjoyed seeing the regenerative farming movement taking off. So many interesting things to explore.”