The podsolic process in soils
1931
Dunnewald, T.J.
The method used failed to show that organic matter leaching explains the accumulation of silica in the surface horizons of podsolic soils. The removal of iron and alumina from the surface horizons and their re-absorption in the subsoil are shown in the acid horizons of three of the soils used. The rapid removal of bases from timbered soil as compared to grass soil is shown and the slower removal of sesqui-oxide as compared to the rapid removal of bases is brought out. Available phosphorus seems to be lost more rapidly into the subsoil of grass soils than is the case with timbered soils. If this method parallels natural processes, it is necessary to conclude that organic matter is not concerned in the podsolic accumulation of silica but is concerned in the translocation of bases and sesqui-oxides. Extraction of the bases and formation of acid conditions appear to be a necessary preliminary to the deposition of iron and alumina in the subsoil. The bases are removed from the surface soil about 20 times as fast as the sesqui-oxides under the same conditions.
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