Chapter 14

Soil Acidity

(book excerpts)

Soil acidity is among the important environmental factors that can influence plant growth and seriously limit crop production. Acidity is due to hydrogen (H⁺) ion concentrations in the soil. The higher the H⁺ ion concentration, the lower the pH. Soil acidification, or a decrease in soil pH, is a natural process that is accelerated by crop production practices, primarily the use of nitrogen fertilizers such as urea, ammonium sulfate, or other fertilizers containing ammonium-N. Acidic soils create production problems by limiting the availability of some essential plant nutrients and increase the soil solution's toxic elements, such as aluminum and manganese. The soil microbes that control nitrogen and sulfur availability also are affected by soil acidity. Management of acid soils involves the adjustment of soil pH to a desired level by liming, adequate irrigation and drainage, and selecting suitable crops. A soil pH between 6.5 and 7.5 provides the best conditions for most agricultural crops.

Click on the following topics for more information on soil acidity.

Topics Within This Chapter:

  • Types of Soil Acidity
  • Active Acidity
  • Reserve Acidity
  • Causes of Soil Acidity
  • Parent Material
  • Acid Forming Fertilizers
  • Crop Production
  • Precipitation
  • Organic Matter
  • Effects of Soil Acidity
  • Nutrient Availability
  • Aluminum and Manganese Toxicity
  • Soil Microbial Activity
  • Soil Physical Properties
  • Liming Acid Soils
  • Liming Materials
  • Carbonates
  • Lime Forms
  • Oxides
  • Hydroxides
  • Lime Quality
  • Calcium Carbonate Equivalence
  • Total Neutralizing Value
  • Effective Neutralizing Value
  • Fineness
  • Moisture
  • Buffer pH
  • Stratification of Soil pH
  • Methods of Application
  • Dry Bulk Limestone
  • Liquid, Fluid or Suspension Lime
  • Precision Agriculture