Historical Developments in Soil Chemistry: Ion Exchange

Abstract The early development of ideas on cation exchange from 1850 to 1900 is described. From 1900 to the present, the coverage has been divided as the work has concentrated on soil acidity, alkali soils, and classical cation exchange studies. The discovery of crystallinity in soil clays and the rediscovery of the importance of noncrystalline oxides adsorbed on crystalline clay minerals as sources of pH‐dependent acidity and anion exchange are reviewed. Some of the more important contributions made in understanding ion exchange in soils are covered in some detail. Other contributions are mentioned. It is concluded that despite the progress made, our understanding is still far from complete.