Influence of dolomite lime on leaching and storage of C, N and S in a Spodosol under Norway spruce (Picea abies (L.) Karst.)

Dolomite lime (8750 kg ha(-1)) was applied in a replicated field experiment (n=4) in a Norway spruce stand in southern Sweden (56 degrees 24 'N, 13 de grees 00 'E). The soil was a Typic Haplorthod. Soil pH and effective base s aturation increased significantly in the forest floor and mineral soil 10 y ears after the lime treatment. The estimated C mineralisation rates (hetero trophic CO2 respiration) in the forest door were 1000 and 1800 kg C ha(-1) per year in the control and lime treatment, respectively. No significant tr eatment effects were found on soil storage of C, although a decline in C st orage was strongly indicated by significant declines in the C/N and C/S rat ios in the Oe+Oa layer of the lime treatment (20.2 and 203, respectively) c ompared to the control (24.5 and 222). The S/N ratio was the same in the tw o treatments (0.11), indicating that N and S were mineralised in the same p roportions in both treatments. Increasing concentrations of dissolved organ ic and inorganic C, N and S forms associated with the lime treatment were f ound at several soil depths. The most consistent effect of treatment, compr ising both C, N and S, was found in the soil solution from the O layer (OiOe+Oa) and at 15 cm depth in the mineral soil. The chemical composition of the dissolved organic matter changed with increasing soil depth. On a perce ntage basis, operationally defined hydrophilic compounds tended to increase , while hydrophobic compounds decreased significantly, indicating a selecti ve adsorption of hydrophobic compounds, particularly in the B horizon. Hydr ophilic compounds tended to have a lower C/N ratio than hydrophobic compoun ds. This difference was statistically significant at the 30 and 50 cm soil depth in the control treatment. Changes in the chemical composition related to the lime treatment could not be shown. Estimates of the adsorption in t he B horizon of dissolved components from the forest floor (annual water pe rcolation 400 mm) showed that the adsorption of DOC and DON was higher in t he lime treatment (202 kg C ha(-1) per year and 7.6 kg N ha(-1) per year) t han in the control treatment (128 kg C ha(-1) per year and 3.4 kg N ha(-1) per year) which accounted for 83-90% of the DOC and DON leaching from the f orest floor. The adsorption of DOS was only 31% (control) and 14% (lime), c orresponding to 0.8 and 0.6 kg S ha(-1) per year, respectively. The DOC lea ching from the B horizon (at 50 cm depth) was equivalent to ca. 1.2% of the estimated annual heterotrophic CO2 respiration. while the DOC adsorption w as equivalent to 6-7% of the respiration. (C) 2001 Elsevier Science B.V. Al l rights reserved.