Studies show that volcanic rock dust can raise the pH of overworked soils, improving productivity.
Credit: UNDO.

Across the country, farmers are taking a chance on a new method: adding crushed volcanic rock to fields to improve soil health (and sequester carbon in the process).

Chris Rauch was strolling past booths at the annual ag show in Spokane last summer when he spotted a large jar full of basalt powder. A nearby sign urged him to spread it on his croplands to help improve soil pH. 

Rauch looked at the gray dust and shook his head. 

“That’s crazy,” he thought. “Why would I want to put even more rocks in my fields?”

Rauch grows dryland wheat in the rolling gold-brown hills surrounding the Pendleton, Oregon, municipal airport. His farm lies on the Columbia Plateau, a 63,000-square-mile basin formed by ancient basalt lava flows. At the end of the last Ice Age, retreating glaciers scoured the bedrock, leaving a wake of grit and gravel to form the deep loess soil. 

Not much rain falls in this grassland habitat. Some years, it’s 9 to 12 inches, […]

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