Charge characteristics of soil organo-mineral complexes and their effect on phosphate fixation

Soil is a complex system of mineral and organic components. The main reactive constituent of the mineral portion of soil is clay and of organic portion is humus from the microbial transformation of organic materials in the soil. Most of the biological and physico-chemical properties and the reactions of soil are due to clay and humus, the colloidal fraction of which being the most important. Many soil phenomena of great practical and fundamental importance such as sorption and exchange of ions, interaction with organic materials etc. originate from the surface charge of clay. The presence of organic matter in the soil and its union with the mineral portion affects these charge characteristics thus affecting many important physicochemical reactions in the soil.