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).