Rapid Acid and Base Titration of Soil for Determination of Exchangeable Cations and CEC

Abstract

Exchangeable base were titrated directly in a soil suspension with hydrochloric acid to pH 2.00 using an automatic titrator under standardized conditions. Titratable acidity was determined by direct titration with sodium hydroxide to pH 7.00 in a suspension of soil and neutral ammonium acetate. It was found that when the CEC at pH 7.00 an the % base saturation were calculated according to the results of the two titrations, there was better reproducibility than when the ammonium chloride-imidazole extraction procedure of Nömmik (1974) was used. The discrepancies between the two methods, when applied to Swedish cultivated soils, were elucidated and discussed. The theoretical grounds for titration of exchangeable cations to pH 2.00 were also given.

Key Words:

• Exchangeable cations
• CEC
• base saturation