The article deals with laboratory experiments of humus containing soil samples that were tested for leaching of iron and lime. The humus and soil samples were collected in five different areas in Silesian state forests, Germany.
The chemical content of the extracts was measured in the beginning of the test. The flocculation experiments and experiments in glass tubes took place. The stronger or weaker the podsolization, the greater or smaller was the protective action of hums at the respective place. However, more research is needed. The results of the glass tube experiments seem to indicate that with humus there were smaller amounts of Ca and Fe leaching than with merely water.