Initial effects of lime and rock powder application on soil solution chemistry in a dystric cambisol - results of model experiments

The initial effects of practical orientated lime and rock powder treatments on soil solution chemistry of a dystric cambisol are assessed by percolation experiments with undisturbed soil cores. During percolation coarse macropores remained air filled (water suction 10-60 hPa). This method may be seen as a 'pedological tissue test' where in a time-lapse-experiment effects and side effects of forest fertilizations are monitored by analyzing the macropore water flux with high spatial resolution. Lime application caused a DOC-mobilization in the Ah horizon and an additional nitrification in the Bv horizon. The DOC formation is triggered by the need to replace unstable bicarbonate anions when the pH of the macropore water decreases drastically. The lime induced DOC output from the Ah horizon is a potential energy source for heterotrophic nitrifiers in the Bv horizon and may explain the additional nitrate formation. Rock powder addition caused mainly an increased K-flux into the mineral soil and showed no significant side effects. However, benefits comparable to liming can only be obtained, if rock powder is applied in 3-4 times higher dosages.