Lime Effects on Pine Forest Floor Leachate Chemistry and Element Fluxes
- Bernd Marschner *,
- Karl Stahr and
- Manfred Renger
In a 30-mo field study, element inputs with throughfall and litter and leachate outputs from forest floor lysimeters were monitored in a control and a limed + K/Mg-fertilized plot in a 40-yr-old pine plantation on a Cambic Arenosol. In the control, input-output budgets show the retention of most elements, which probably is a natural phenomenon in this young ecosystem and not caused by inhibitory effects of anthropogenic inputs on decomposition processes. Despite the high Ca status of the forest floor, the H+ inputs of 70 to 90 mmolc m−2 yr−1 are buffered only to a small degree (0–30%). Internal H+ production from dissociation of organic acids and N transformations contributes up to 130 mmolc m−2 yr−1 to the acid load in the leachates. As a result, Zn and Cd are mobilized from the forest floor. In the limed plot, the applied K and Mg sulfates were washed out quantitatively within 1 yr. Due to the high solubility of the chalk-lime, leachate Ca concentrations rose sharply and pH increased from 4.0 in the control to over 6, showing that acid from inputs and from internal production was almost completely neutralized. After a partial N immobilization in the 1st yr, total mineral N outputs were similar in both treatments. But in the limed lysimeters, the degree of nitrification in the leachates reached 85 to 95% compared to 30 to 55% in the control, which has consequences for N availability and for N leaching in the mineral soil. The retention of Cd and Zn was greatly increased by the treatment and reached 60 and 30% of total inputs, respectively.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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