Soil Acidity on the Palouse Workshop – Digging Deeper

View details and registration for the workshop.

View the Soil pH Workshop presentation details (pdf) in PDF format.


WSU Farmers Network and Wheat & Small Grains Dryland Cropping Systems will be hosting a workshop on January 4th, 2018, at Banyans on the Ridge in Pullman, WA. The aim is to present the most up to date, information on soil acidity in our region.

Topics will include a brief overview of the basics of soil acidity on the Palouse and move into more in-depth information based on current research from local experts. Presenters will speak on effects of soil pH on soil health, remediating soil acidity with lime- does it work? and how much to apply, economics of low soil pH soils, and a panel discussion on how low soil pH can affect soil microbial communities, soil born disease, and herbicide resistance.

Addressing soil acidity is a new challenge for the Palouse region, this workshop is designed to accommodate participation by attendees, provide the opportunity to get questions answered, and share knowledge gained from growers’ experience. This workshop has been approved for 8 CCA credits and will provide continental breakfast and lunch.

Soil acidification accelerated by the addition of ammonium-based fertilizers is a growing concern in the Pacific Northwest (PNW). The native soil pH was near-neutral but has been continuously declining since fertilizer N production begun in 1960. Survey’s conducted in eastern WA and northern ID found that the average soil pH and the top 12-inch soil depth was <5.7 in 1984 and <5.2 in 1995. In an additional survey of 73 no-till fields in Columbia County, WA, 97% of those fields had a soil pH <5.2 in the top three inches and pH <5 between three and 6-inch soil depth.

Soil acidification alters soil chemistry, fertility, and soil microbes, which in turn, have major effects on soil health and crop production. Some soil acidity effects on soil and plant health are:

  • The availability of all essential nutrients, except iron, are significantly reduced at soil pH <5
  • Because fungi adapt better to acidic conditions when soil pH decreases, the soil microbial community loses a healthy balance between beneficial bacteria and fungi, and becomes fungi-dominated
  • Cephalosporium stripe can increase five-fold when soil pH decreases from 7.5 to 4.5
  • Soil’s N-fixing capacity is significantly reduced due to reduced Rhizobia survival and activity
  • In the long run, soil acidification shifts cropping systems because all crops have a maximum tolerance level for soil pH, but not all crops or crop varieties are sensitive to low pH.

For more information on soil acidification, the WSU Small Grains website has compiled a body of extension publications, including soil acidification videos that provide an overview of the basics of soil acidification and management of acidified soils.


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