Abstract
AbstractIn 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.
Published Version
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