LTER Zöbelboden, Austria, Soil chemistry, 2014

The soil data originates from the soil sampling of the mineral soil (0-10cm) at 64 plots across the entire study area in 2014 .
After litter removal, composite samples were made from three individual soil cores (4 cm diameter). The soil cores were taken 2.5m distance to the 1992 and 2004 sampling points.

In the laboratory, soil samples were dried at 30°C, coarse aggregates crushed and dried again until con-stant weight. Subesequently, the samples were sieved through a 2 mm sieve. Soil suspensions were made by dissolving 5 g of each soil sample in 12.5 ml of 0.01 M CaCl2 solution and pH was measured electrochemically with a pH electrode (Argus X pH meter in 2014). For the determination of the C:N-ratio the soil samples were ground and further decarbonized using 3M HCl solution. The organic carbon content was measured after dry combustion using isotope-ratio mass spectroscopy (IRMS). This methods deviate from the analysis in 1992 where total content of organic C (TOC) was calculated by subtracting the total content of CaCO3 from the total content of C (TC – TIC). Total content of C (TC) was analyzed by dry combustion (1300°) of the samples in O2. Released CO2 was detected coulometrically (Ströhlein Coulomat 702 and Si 111/6). Total content of CaCO3 (TIC) was measured via addition of HCl and volumetrically determination of the released CO2 (Scheibler). The total content of N was determined by a modified Kjeldahl method and did not deviate from the methods in 1992 and 2004. The organic N was converted to NH4+ by digestion with H2SO4 and a catalyst (Kjeldahlterm KT8 Gerhardt). The accumulated NH4+ was converted to NH3 (distillation) and measured by potentiometric titration. To account for N oxygen com-pounds, salicylic acid was added prior to digestion.