ABSTRACT
The oxidation-reduction potential, or electron availability, influences the oxidation states of hydrogen, carbon, nitrogen, oxygen, iron, and sulphur, and of trace metals like manganese, cobalt and copper. In consequence, the varying degrees of free exchange of oxygen between the soil and the atmosphere are fundamental in creating distinctive soil properties and profile characteristics. Soil formation is determined in many ways by the character and intensity of oxidation-reduction processes. Oxidation processes occur at the expense of either free oxygen, or soil constituents able to release oxygen or to take in hydrogen. A significant part of the sorptive capacity of many soils for cations and for proton-accepting molecules resides in the humus fraction of the soil. A buffer is a solution which minimizes changes which would otherwise occur towards either increasing acidity or alkalinity in the soil, and the presence of calcium and magnesium too is important in maintaining near-neutral conditions in the soil.
