A seminar will help farmers with low pH in their soils in February.

Washington State University Farmers Network hosts a soil acidity amelioration workshop from 7:45 a.m. to 3:45 p.m. Feb. 21 at Banyans on the Ridge in Pullman, Wash. The event will accommodate 75 to 100 people.

After years of nitrogen fertilizer applications, the average pH in the top 12 inches of soil in the Pacific Northwest dropped from near neutral to less than 5.2 by 1995, according to WSU. A 2014 soil study found that 97 percent of surveyed minimum-till and no-till wheat fields in Columbia County had a soil pH of lower than 5 at 3-6 inch soil depths.

The problem is particularly bad in the Palouse area, said Haiying Tao, WSU nutrient management specialist.

"In higher rainfall areas, the yield is high, which means you require a higher amount of nitrogen," Tao said. "The more nitrogen you apply, the more acidification effect this nitrogen fertilizer has."

High-rainfall areas are subject to leaching, which leads to further problems. Nitrogen leaching means other nutrients are also lost, Tao said. Low soil pH can affect root development, soil microbial populations and herbicide efficiency, she said.

The February workshop zeroes in on soil pH, more than a soil health workshop scheduled for January, Tao said.

Use of agricultural lime is a common practice for raising soil pH elsewhere in the country, but in the Pacific Northwest access to low-cost lime is limited.

"If you have lime nearby, the material itself is not that expensive," Tao said. "Transportation costs are just so big."

Northwest farmers don't have the necessary equipment, she added.

WSU is exploring locally available low-cost alternative materials, Tao said. Other industries may offer waste byproducts for free or at a cost.

The amount of lime needed depends on how low the soil pH is, what type of soil it is and the amount of organic material and clay in the soil.

WSU Extension offers a soil pH calculator.

Tao said the problem can be solved.

Field Reporter, Spokane

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