The ancient technique that could save a vineyard from ruin
Could biochar be the next big ingredient in regenerative agriculture? California grape growers and grape growers are beginning to discover 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 rich in organic carbon whose primary purpose is soil improvement. It is also a useful tool in the fight against climate change.
As head of the Sonoma Ecology Center and director of the Sonoma Biochar Initiative (SBI), Raymond Baltar tries to spread the word.
“Biochar is a key ingredient in a new carbon-negative strategy that offers solutions to many of today’s critical ecological, energy and economic challenges,” says Baltar. “It is not a fertilizer or a food source for plants or microbes. The use of biochar in soil is new, exciting, and not yet fully understood.
To create biochar, waste materials from agriculture and forestry, such as vine cuttings or felled trees, are burned under intense heat managed to maximize their carbon and convert the materials to a form as pure as possible.
“One of the many ways we are building the health of our soils is by integrating the application of biochar into our vineyard management program,” says Tony Chapman, 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 combustion process, the material cools and is mixed with Donum compost. Then it is applied to the vineyard.
“Because biochar is highly porous, lightweight, and has a large surface area, it has been shown to increase water retention, improve soil structure, improve porosity and microbial properties,” adds Chapman. “The carbon that the vines have fixed from the atmosphere for photosynthesis is removed from the carbon cycle and stored in the soil through biochar and other organic matter.”
Donum transitioned to organic farming in 2019 and will receive California Certified Organic Farmers (CCOF) certification this year. Additionally, they have embraced the fundamentals of regenerative agriculture, including livestock integration and composting, as well as biochar.
There are high-tech and low-tech ways to create biochar, but ultimately the goal is to burn hot and reduce smoke, preserving the material as solid carbon rather than leaving it behind. escape into the air in the form of smoke.
“Biochar is the byproduct when biomass is burned or heated with minimal or no oxygen,” Baltar explains. “Recently, archaeologists discovered that indigenous tribes in the Amazon rainforest used char to enrich the soil 500 to 4,000 years ago. The Japanese used arctic char in the soil for centuries before it recently replaced by chemicals and industrial methods.
“Biochar is a key ingredient in a new carbon-negative strategy.”—Raymond Balter, Director, Sonoma Biochar Initiative
Although an old technique for improving soil health, biochar was first included as a promising negative emissions technology in a 2018 special report by the Intergovernmental Panel on United Nations Climate Change (IPCC).
Hans-Peter Schmidt, research director at the Ithaka Institute in Ayent, Switzerland, further explained the potential of biochar for environmental health in the Biochar Journal.
“To maintain global temperatures within the range that has sustained civilization over the past millennia (1.5°C threshold), the carbon balance between emissions to the atmosphere and carbon accumulation in the Earth system must return to equilibrium by 2050 at the latest,” Schmidt writes. “To achieve this, greenhouse gas emissions must be reduced by at least 90%, with the global economy becoming climate neutral by 2050.”
The 2022 IPCC Special Report reiterated this point, naming biochar as one of the three least expensive methods of large-scale atmospheric carbon dioxide removal, along with reforestation and sequestration.
“I love biochar,” says Graeme MacDonald of MacDonald Vineyards in Oakville in Napa Valley. “Native Americans did a lot of controlled burns in the valleys which helped build fertility for generations. I loved seeing the regenerative agriculture movement take off. So many interesting things to explore.