SCHRIFTENREIHE Institut für Pflanzenernährung und Bodenkunde ...

UG 79 is assumed to be the result of a sandier parent material. However, the
coarse-textured topsoil in HG might be partly attributed to erosion of fine
particles by wind from the predominantly bare ground. In the topsoil, bulk density
increases with increasing grazing intensity, indicating the effects of mechanical
stresses on soil structure induced by animal trampling. At the ungrazed sites,
bulk density is much higher in the second soil layer compared to the topsoil. This
is a sign that the upper soil layer has obviously recovered from previous sheep
trampling. Compared to the other three sites, the total C-content (4-8 cm) in HG
is reduced by about 50%, which may be due to both wind erosion of particulate
organic matter and higher mineralization rates.
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Table 5.2. Soil texture, bulk density and organic carbon content of the four sites.
Site
Soil depth Sand Silt Clay
Bulk
density
Organic
carbon
(cm) (%) (%) (%) (g cm -3 ) (g kg -1 )
UG 79 4-8 59.0 27.5 13.5 1.14 22.0
18-22 66.1 21.2 12.7 1.39 16.5
30-34 75.3 14.6 10.2 1.42 10.1
40-44 78.2 12.5 9.3 1.40 8. 2
UG 99 4-8 52.5 31.0 16.5 1.11 19.6
18-22 59.1 26.9 14.0 1.33 23.1
30-34 54.8 29.9 15.3 1.34 15.9
40-44 56.5 28.1 15.4 1.27 15.0
WG 4-8 49.8 32.2 18.0 1.28 22.2
18-22 54.9 28.0 17.1 1.29 13.2
30-34 54.7 29.7 16.6 1.24 11.4
40-44 54.9 27.9 17.3 1.25 11.6
HG 4-8 65.8 21.6 12.6 1.30 11.8
18-22 73.2 16.0 10.7 1.42 7. 2
30-34 71.3 17.2 11.6 1.43 6. 5
40-44 72.8 16.6 10.6 1.45 6. 0
Water Retention Characteristics and Hydraulic Conductivity
Total pore volume generally decreases from the topsoil layer to the subsoil
for all sites (Fig. 1). In the topsoil, the total and large pore (>50 μm) volumes
significantly decrease with increasing grazing intensity. Especially, HG shows a