pH Levels and Liming Products by Shawn Wallace

Somewhere over the years the first thing you learn about cropping systems has become confusing with all the products that “claim” to be liming agents, or even worse, overlooked. The pH level in every soil system is dynamic, changing consistently in season and annually. The gains of organic or commercial fertilizer, precision technologies, or herbicides can never fully be quantified if the pH levels are not correct! Let us quickly recap why the soil pH level is important and how to ensure we are selecting the best product for corrective measures in our soils.

The pH of the soil is the measurement of the hydrogen ions (H+) in soil solution when shaken in distilled water, and each unit increase in pH is a 10 times the change in acidity (a pH of 6 is ten times more acidic than a pH of 7). Soils are “neutral” at a pH level of 7. As soil structures become increasingly acidic (or decrease in pH level), our important “Macro” nutrients like Nitrogen, Phosphorus, and Potassium become less available for plant uptake, which can result in a dramatic reduction in yield. In the more acidic soils other elements, like Aluminum or Iron, become more available and may become toxic to the plant resulting in reduced yields.

Liming to the desired pH of the crop being grown not only increases availability of essential nutrients, but also supplies additional calcium and magnesium, improves soil conditions for microorganisms, increases the effectiveness of herbicides, and improves soil structure.

Understanding the pH level needed for optimal yields is one part to the equation but comparing the different liming products on the market is crucial when factoring in your return on investment. The two most important components to a lime are the Calcium Carbonate Equivalent (CCE) and Fineness (or Mesh Scores). When these two percentages are factored together, you end up with the Effective Neutralizing Value or ENV%. This value is used to determine the amount needed to change the pH of the soil. A lower ENV% will require more product to equally change a product with a higher ENV%.