INVESTIGATION OF NITRIFICATION IN FOREST SOILS WITH SOIL PERCOLATION COLUMNS

Soil percolation columns in which a pF of 2 could be maintained were developed to study nitrification in soils and litter of an acid and a calcareous forest soil location. High nitrification rates were observed in the calcareous soil. In the acid soil nitrification was much slower. A column filled with leaf litter gave a low nitrification rate at the start of the experiment, but a high rate was found after 60 days of percolation with an ammonium-containing medium of pH 4. In this leaf litter high numbers of autotrophic bacteria were just present at the beginning of the experiment, whereas at the end only low numbers were detected. Results indicate that autotrophic bacteria from acid soils are sensitive to a pH increase. © 1990 Kluwer Academic Publishers.