Burning Vineyard Waste for Biochar
Done correctly, method creates little smoke and leaves usable soil amendment behind
San Rafael, Calif.—Advocates of the natural soil amendment biochar say vineyard trimmings and pulled vines make an excellent source for the material.
And if growers use a particular method when burning piles of dead vineyard material, they can also limit the amount of air pollution from the fire while making the charcoal credited with providing a host of beneficial effects on soil including water conservation, enhancing soil nutrients and providing stable organic material for healthy plants.
Using burn piles to create biochar wouldn’t create enough of the material for regular amendments or the recommended amount to help a developing vineyard, but it would be a more effective way to get rid of vineyard waste and create something good for the ground.
Alex Crangle, winemaker for Balo Vineyards in Philo, Calif., has been making his own compost with winery and vineyard organic waste since 2012. Two years ago he started using the method of “conservation burning” for his burn piles. The approach is recommended by the Sonoma Biochar Initiative and is a way to burn a waste pile that leaves biochar at the end without creating too much smoke.
Crangle doesn’t get much biochar—the charcoal makes up about 2% of the two tons of compost he applies per acre—yet he believes even a little can help. “Biochar helps buffer soil pH and increases overall bioactivity in the soil by creating nucleation sites for microflora and sequestration capacity for nutrients,” he said in an email to Wines & Vines. “It's not something we expect dramatic results from in the short term, but the goal is long-term soil health and vitality, which I feel we are achieving.”
Crangle invited three biochar experts to discuss the material and conservation burning at this year’s Anderson Valley Pinot Noir Festival in Boonville, Calif. The panel included a supplier of the material and two proponents of biochar who have long been advocating its use as a way to help the environment and improve yields.
A cleaner, less smoky burn
The biggest benefit of conservation burning is that it’s a much cleaner way to dispose of burn piles, says Raymond Baltar, the director of the Sonoma Biochar Initiative who heads up three other biochar programs in California. “It is first and foremost a pollution-reduction technique that can also yield biochar and allow farmers to sequester some amount of usable carbon,” he said.
Baltar mentioned one large Sonoma County winery that estimated it generated about 2 tons of biochar from five relatively large piles, although small vineyards with may not generate anything more than a small amount to be incorporated into compost.
To create an effective conservation burn, the dead vines and cuttings need to be dry, so piles should be left to season for a year. Once ready, he recommended using a clean-burning propane torch to light the wood at the top of the pile. If it’s a windy day, the pile should be lit on the downwind side. As the flames burn down into the pile, they produce less smoke and help retain the beneficial carbon. “Just looking at it, it’s amazing how little smoke is actually produced,” he said.
Baltar regularly leads training sessions at North Coast vineyards so vineyard managers can see firsthand how best to use the methods.
If one is hoping to create some biochar, Baltar said it’s a good idea to have a piece of earth-moving equipment and a water truck to put out the fire quickly and then move the burnt material. “Biochar made this way is generally in large chunks that need to be reduced in size to maximize surface area, and there are a number of ways to do this,” he said. “Probably the best way is collecting the biochar, spreading it out on a cement surface and running over it with a small construction roller, but some just drive over it numerous times with a truck or excavator.”
Once the material is ground up, it needs to be inoculated, and Baltar stressed this was a vital step. He said the simplest way to do this is to incorporate biochar into compost and then let it “cure” for several weeks while keeping it moist. “The longer the biochar is allowed to cure the better, which then allows it to start working its magic when put in the soil rather than requiring a period of adjustment,” he said. “Since biochar is very stable and degrades very slowly, it can just be saved and blended for later use if need be.”
‘Enhanced compost’
Josiah Hunt, a Hawaiian farmer who founded Santa Rosa, Calif.-based Pacific Biochar, said the material needs to be tilled into the soil, and an ideal time to add it is when applying compost. He suggested 10% to 20% of compost (or a quarter to half a ton per acre) is good for maintaining soil health, and 20% to 40% or between 4 tons and six tons per acre for major events such as planting. “You can think of it as enhanced compost with carbon,” he said.
The full benefits of biochar often aren’t seen until the third or fourth year of application, but Hunt referred to an Italian study on biochar amendments to a dry-farmed vineyard that saw a nearly 40% increase in yield and generally did even better with less rainfall. “We’re finding a lot of benefits to this,” he said.
Dr. David Morrell, operations director at the Sonoma Ecology Center, extolled biochar as not just a beneficial vineyard product but as a possible way for California efforts to address global climate change. He said the more than 100 million trees that have died from the drought and disease could be converted into usable biochar. If those trees aren’t used productively, they could burn up in a forest fire, and all that carbon would be released into the atmosphere.
The biochar produced from the trees would then help California’s farmers produce more food and use less resources to do it. “When that happens, we have free carbon sequestration,” he said. “It’s time for California to set a model in place. If not here, where? If not now, when?”
