To Reverse a Troubling Trend, Farmers Are Adding Rocks to Their Fields

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, but lately, it’s more like 6 to 9. Pre-cultivation, the region owed the healthy pH of its soils to the lucky coincidence of sitting atop a volcanic bed. However, the topsoil is powerless to counteract the acidifying effect of ammonia-based fertilizers. Over the years, this has caused pH levels to drop to 5 and below, according to Dr. Francisco Calderon, director of the Columbia Basin Agricultural Research Center.

“It’s not a widespread problem yet, but it’s rearing its ugly head in some places,” says Calderon.

A few weeks after the ag show, Rauch got the latest results of his soil pH tests: 5.3. He recalled the message from the ag show booth, run by a company called UNDO. The crushed rock raised soil pH levels. And it was free. 

His first thought was, why? It seemed too good to be true. Yet the more he read, the more it seemed legit.

“You can’t beat zero,” he finally decided, and gave UNDO a call. 

Rauch is one of many farmers taking a chance on a new