Winery works closely with the earth

White silica powder, made by grinding up quartz rocks, was mixed with water and sprayed on the grapes last week at the Benziger Family Winery's vineyards on the flank of Sonoma Mountain.

The silica crystals, after a summer buried in cow horns at the ranch, cling to the vines and amplify sunlight hitting the leaves just before harvest, according to biodynamic farming principles.

In another biodynamic practice that skeptics equate to voodoo, cow manure-packed cow horns are buried underground over the winter, producing a microbe-laden humus that enriches the soil.

Biodynamics envisions a "life force" permeating the ranch and invigorated by homeopathic treatment on a grand scale, applying compost tinged with substances like yarrow, camomile, stinging nettle, dandelion and oak bark.

Circles and rows of colorful, aromatic and drought-resistant plants and flowers - called "insectaries" - are planted amid the grapevines. Mexican sage, lavender, echium and other plants attract predatory bugs that devour vineyard pests in a purely natural way.

Owls and bats are given housing in exchange for feeding on rodents. Sheep eat the cover crop from the vineyard, replacing tractors, and depositing recycled nutrients in their feces.

Benziger Winery will bottle about 13,000 cases of certified biodynamic wine this year and next. "I can't look you in the eye and say it's better," said Mike Benziger, head of the family-owned winery. "I can say it's different."

Making biodynamic wine isn't about "technical perfection," Benziger said. "It's about an authentic vintage, an authentic place."