Acidification

Soil acidification is when soil pH gets lower (below pH 7) over time. It occurs naturally as soils weather and “base cations” such as calcium (Ca²⁺) and magnesium (Mg²⁺) are leached or lost through plant removal, but acidification can be exacerbated with continuous use of ammonium-based fertilizers because ammonium produces H+ ions as it converts to nitrate. When soil pH drops to 5, aluminum toxicity becomes a major issue.

Resources

Soil pH and Implications for Management: An Introduction. Carol McFarland, David huggins, Richard Koenig. 2015. Washington State University. FS170E.

Small Grains soil acidification video series. A series of three short videos featuring growers and local researchers explaining the challenges, symptoms, causes, and implications for farm management that are associated with soil pH decline.

Soil Acidity: It’s not just pH. PowerPoint slide lecture from Wheat Academy. By Jim Harsh.

Soil Acidity Impacts Beneficial Soil Microorganisms. Tarah Sullivan, Victoria Barth, Rick Lewis. 2017. FS247E. Washington State University.

Soil Acidity on the Palouse. Workshop website. 2018.

Changing soil pH. Two-page publication. Paul Vossen. University of California Cooperative Extension.