Acid-base buffer characteristics of soils of spruce rhizosphere in the AE-horizon of podzolic soil

In samples taken from the AE-horizon of podzolic soil in the rhizosphere of spruce and the area external to it, the general chemical parameters and buffering to acid and base were determined by continuous potentiometric titration. It was found that the rhizosphere soil is characterized by significantly (at P = 0.9) higher general buffering to the base as compared than is that outside the rhizosphere zone due to increased pH values in the range of 9 to 10. This is explained by the large amount of organic matter, and probably mobile compounds of iron and aluminum, in it. During titration by the base, it is assumed that the main buffer reactions in this pH range are deprotonation of phenol hydroxides of specific and nonspecific organic acids, as well as of surface hydroxyl groups of minerals of iron hydroxides, and increase in the basicity of Fe- and Alorganic complexes.