[Microbiological investigations into soil in a fertilizer trial with spruce in the fume-damaged zone of the Erzgebirge (author's transl)].

In the heavily fume-damaged spruce stands on crest sites in the eastern parts of Erzgebirge the composition of microbe population and organic matter conversion in the A0 horizon can be positively changed with a lasting effect by fertilization using CaNP. Ammonification, nitrification, urea transformation, and decomposition of cellulose are enhanced by the increased occurrence of bacteria and actinomycetes. As a result of fertilization acidity was reduced from pH (KCl) 3.0 to 3.6 as a maximum. The influence of the nutrient status is clearly manifest in the humus form (raw humus in the case of quartz porphyry, mull-resembling moder in the case of basalt), but scarcely in the chemical and microbiological properties of the Of subhorizon. No pronounced effect of the SO2 fallout on the microbiological conditions in the A0 horizon was observed. The increased soil fertility after application of Ca and P can lead to an increased and a more stable yield of wood only under certain conditions.