“pH is easy to spell, but it’s more difficult to understand,” at least that’s what Dr. Larry Oldham, extension soil specialist at Mississippi State University Extension Service told Mike Howell when he and Dr. Clain Jones, Montana University soil fertility specialist, were guests on The Dirt podKast.
Soil pH characterizes the soil as acidic (0-7), neutral (7), or alkaline (7-14) and if properly managed, can optimize fertilizer use efficiency and crop yield. Soil pH governs many chemical and biological processes in the soil and is something you should consider when developing your nutrient management strategy.
“pH effects a lot of different processes,” said Jones. “Most notably, it affects nutrient availability. For example, in Montana, where our historical pH’s have been around 8, we have very low phosphorus availability and often metal availability such as such as iron.”
A lower pH can present some serious problems as well, especially as nutrients like phosphorus get tied up in the soil. They can become toxic.
With varying problems of low and high pH levels, there are some steps you can take to adjust your soil’s pH. Soil pH can be modified with the addition of fertilizers, tillage practices, soil organic matter, drainage, and soil amendments. Liming should also be considered a regular practice on acid soils below a pH of about 6.0-6.5. Because crops vary in their sensitivity to pH, the crop rotation will be an important consideration in the pH desired.
Lowering the pH of high-pH soils above about 7.5 is much more difficult and often not economical because the pH at these levels is usually dominated by the presence of lime in the soil. Elemental sulfur may be a good option for this process.
Like anything, the best way to manage your soil’s pH is to monitor it. According to Dr. Oldham, that’s vital to growers wanting to adjust their soil pH. “Just keep an eye on the on the situation and use a rigorous routine soil testing program.”
For more in-depth information on soil pH and ways to adjust it on your farm, listen to this episode of The Dirt podKast: The Importance of Soil pH with Dr. Larry Oldham and Dr. Clain Jones.