Biogeochemial Soil Dataset for Old Growth and Disturbed Forest Sites at Mount Kilimanjaro

This dataset presents biogeochemical data (pH, CNS, soil texture, bulk density, extractable metals, cation exchange capacity) from 21 profiles at Mount Kilimanjaro, Tanzania. The data is part of Schrumpf's dissertation ("Biogeochemical Investigations in Old Growth and Disturbed Forest Sites at Mount Kilimanjaro").

Exact sampling locations (WSG84: long/lat) are reported for each profile. Analyses of soil material were carried out on air dried samples (30°C) of the fraction < 2 mm. Soil pH was determined using H20, and 1 M KCl at a soil solution ratio of 1 (m) : 2.5 (v) and a standard combined electrode with integrated temperature probe (WTW SenTix 41 pH 330). Total C and total N contents were analyzed on ball-milled samples using a total element analyzer (Elementar Vario EL). Exchangeable cations (K, Ca,Mg, Na, Al) were extracted by an unbuffered 0.5 M NH4Cl solution (Trüby & Aldinger 1989) and measured by atomic absorption (Varian SpectrAA 400). The ECEC was calculated as the sum of exchangeable base cations and exchangeable Al. At ten profiles in ten main study area between 2100 and 2330 m, Fe and Al in metal-humus complexes (Fep, Alp) were extracted by shaking 2g of soil in 0.1 M sodium pyrophosphate (pH 10) for 16h, followed by centrifugation, after addition of CaCl2. Fe, Al and Si in ferrihydrite, allophane, imogolite and metal humus complexes (Feo, Alo, Sio) were determined in all soils using a 0.2 M oxalate solution (pH 3) (Schwertmann 1964). The cold dithionite-citrate buffer (DCB) method (Holmgren 1967) was used to analyze the amounts of Fe and Al (Fed and Ald) in crystalline oxides and fractions from metal-humus complexes and amorphous constituents. Bulk density was determined on three undisturbed soil cores with a volume of 100 cm-3, which were taken from each soil horizon.