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w w w. v w m m e d i a . c o m M a r - A p r 2 016 | V I N E YA R D & W I N E RY M A N A G E M E N T 7 3 in biochar may be inert, she says, but "when certain microbial popu- lations start gnawing on it, it could start breaking down. With micro- bial populations being so varied, it's hard to say what will happen." Although "the jury is out in terms of how much carbon can be sequestered," says Ngugi, "I'd say the evidence, based on lab and small-scale trials, is pretty compel- ling. The challenge is looking at pol- icies and incentives" to encourage large-scale carbon sequestration. The more pressing question scientists and biochar cheerlead- ers need to answer for growers is: "What's in it for me?" Some researchers have pro- posed that, with a demonstrated carbon baseline, carbon seques- t r a t i o n c o u l d p o t e n t i a l l y l e t a grower participate in California's greenhouse gas cap and trade. As California eventually stepped in to ban the practice of burning rice husks and straw in fields to deter its detrimental effects on air qual- ity, Ngugi says, some similar con- siderations might be made to help connect the good practices associ- ated with biochar use for mitigat- ing climate change and greenhouse gas emissions. This might include adding it as an offset in the emis- sions cap and trade market. Although it's important for grow- ers and vintners "to measure their carbon footprint and consider using practices that reduce emissions or increase carbon sequestration," says Jordan, winegrowers are suf- ficiently efficient and applying rela- tively low levels of nitrogen. "And with relatively high transaction costs for complying with cap and trade, we don't necessarily see an immediate opportunity. This could change, however, if the cap tightens in the future and value of the carbon credits increases," she adds. Understandably, grapegrowers are reluctant to pool their carbon underground just yet. Yealands Wine Group has a long-standing interest in adopting sustainable practices throughout its business. Although interested in converting its vine prunings and grape pom- ace into biochar, "We've yet to applied, but more research is need- ed to fully evaluate any potential concerns or drawbacks regarding vine health and biochar application. Niehues won't be part of this, as she's preparing to graduate. She says the logical next steps for other academics and scientists to take include looking at the real-term availability of carbon over the life- time of a vineyard, not only within growing seasons. More information about many of these topics is available from the California Sustainable Winegrowing Alliance, including Denitrification- Decomposition Greenhouse Gas Modeling for California Vineyards, an online tool for calculating green- house gas emissions. Linda Dailey Paulson is a writer based in Portland, Ore. During her career she has covered water and agriculture as well as the wine industry for various newspapers and trade publications. Comments? Please e-mail us at feedback@vwmmedia.com. produce commercial volumes of biochar," says Hoksbergen. "Our grape prunings are either mulched back into the vineyard or bailed for use in our furnaces to heat winery water, which means significant reductions in our fossil fuel use. We hope to turn prunings into bio- char in the future." Hoksbergen adds, "We're in the process of building a biochar furnace, but we have numerous other engineering priorities with winery expansion, so biochar is on the back burner for now. When we have a suitable volume, we'll mix it with our compost/mulch." WHY SHOULD I CARE? G r o w e r s s h o u l d u l t i m a t e l y care about carbon sequestration because, "Carbon is one of the backbones of soil organic matter. It provides stable soil structures," Niehues says. Healthy soils make for healthy vineyards. UC Davis researchers did see significantly more leaf nitrogen in those plants to which biochar was The benefits associated with biochar application in vineyards aren't limited to carbon sequestration. To overlook these other pluses, say experts, is short-sighted, as the compound has numer- ous positive properties as a soil amendment. "Carbon sequestration is one of a laundry list of [biochar's] ben- efits," says Bruce Gradek, viticulturist at Cool Planet, maker of an engineered biocarbon soil amendment. "Is sequestering carbon the first thing a grower needs from biochar? Probably not." As a soil amendment, biochar is most notable for its ability to help the soil retain both water and vital nutrients. Where biochar appears to be best applied in vineyards are in those areas with poor soil quality, says Gradek. One example of this is a CoolTerra client now using biochar to stimulate soil microbial activity in two treasured blocks of old vine Zinfandel. Through applying biochar, Gradek says, the grower is hoping to keep those vines healthy and producing. "Outside of the yet-to-be-proved carbon benefits, we believe biochar has other useful properties in terms of its role in improv- ing soil structure, water holding capacity and capacity to hold nutrients and mitigate leaching," says Tony Hoksbergen, general manager – viticulture at Yealands Wine Group. "I believe there's no debate about these benefits."– L.D.P. BIOCHAR'S OTHER BENEFITS