As soil acidification continues to be a concern for growers in the Pacific Northwest, WSU researchers are working to provide information and recommendations for how to mitigate adverse effects. Root diseases are one of many factors influenced by acid soils, depending on the soilborne pathogen. The new publication, Acid Soils: How Do They Interact with Root Diseases?, explains how soil pH affects root diseases and also offers examples of common ones in the Pacific Northwest.
Cereal growers in the Pacific Northwest have been experiencing an increase in soil acidity (lower pH) primarily due to a long history of ammonium fertilizer use.
In eastern Washington and northern Idaho, soil acidification tends to be worse in areas that are annually cropped, do not include nitrogen-fixing legumes in the crop rotation, and in areas that were historically forested. Forested soils tend to have a lower pH buffering capacity, making them more prone to shifts in soil pH. These same areas also typically include more forage and seed grass production and seldom include legumes in rotation, meaning that there is more intensive nitrogen application to the soil.
In addition, direct seeding can result in a stratification of soil pH in which the top few inches of soil are more acidic. This is because acidification caused by fertilizer application in the top soil layers is not diluted by mixing with the more alkaline soil below the fertilizer zone. However, the contribution of this stratification on management of soil acidity in direct-seed systems has not been evaluated.
For questions or comments, contact Tim Paulitz at USDA-ARS Wheat Health, Genetics and Quality Research Unit (firstname.lastname@example.org or email@example.com) or Kurtis Schroeder, Assistant Professor in the Department of Plant, Soil, and Entomological Sciences at the University of Idaho (firstname.lastname@example.org).