2.2. 1 Field and sampling methods
5 CDs, representative for this study area, were chosen for detailed soil profile and SOC measurements. At the bottom of each CD (i.e. its deepest point), a 160-220 cm deep soil profile pit (outcrop) was dug, reaching the lower boundary of the soil horizons (Figure 3). Next, identification and documentation of soil horizons and colluvial layers in the exposures were made. All outcrops were described, according to standard methods (Guidelines for soil descriptions, FAO, 2006).
Bulk samples of soils and sediments were collected from each horizon in the wall of the exposures for laboratory analysis. One to four samples were collected from each of the horizons distinguished, depending on their thickness.
A total of 103 soil samples were collected from 5 soil profiles, all located in the bottom of the studied CDs. The samples were air-dried, crushed with a mortar, sieved at 2 mm and stored in plastic bags.
Furthermore, 20 to 30 control augerings were carried out in each CD to determine the areal extent and thickness of colluvial sediments (C1, C2) and fossil soil horizon (A, Bh, Bt) extension. Augerings were located in two cross-sections of each CD (Figure 3).