You must log in to edit PetroWiki. Help with editing

Content of PetroWiki is intended for personal use only and to supplement, not replace, engineering judgment. SPE disclaims any and all liability for your use of such content. More information

Glossary:Exchange acidity

Jump to navigation Jump to search

The titratable hydrogen and aluminum that can be replaced from the adsorption complex by a neutral salt solution. Usually expressed as milliequivalents per 100 grams of soil. Acidity in a soil is primarily the result of hydrogen ions (H+), aluminum ions (AI+3), and aluminum mono and di-hydroxide ions [AI(OH)+2 and AI(OH)2+1, respectively]. Because they have a positive electrical charge these ions participate in cation exchange reactions, and because they cause soil acidity they are called exchangeable acids. Exchangeable acidity is therefore the number of meq/100 grams of soil which consist of hydrogen, aluminum, and aluminum mono and di-hydroxide ions. The remainder of the cation change capacity would consist of exchangeable bases such as sodium, potassium, calcium, and magnesium. The role of aluminum ions in acidity is described in the definition of reserve acidity.