| dc.description.abstract | Natural processes and anthropogenic activity threaten soil as a resource.
Soil degradation is a global problem intensifi ed by climate change, population
growth and economic development. Soil erosion is one of the
most prevalent forms of degradation in Serbia. Soil resistance to erosive
processes largely depends on the soil‘s physical properties. Erosion processes
aff ect changes in the physical characteristics of the soil. Therefore,
the hypothesis is established: There is a diff erence between the physical
parameters of soil aff ected by erosion processes and soil on which there
are no visible indicators of the action of these processes.The investigated
area is located in the southern, hilly part of Belgrade, in a degraded
forest area vegetated by Hungarian and Turkey oak (Quercetum frainetto
– cerris). Intensive landslide and gully erosion processes aff ect this area.
The mechanism of occurrence of the erosion process is piping-erosion.
Thirteen transverse profi les were selected on gullies where soil sampling
was performed. Sampling was performed on each profi le in the gully
bed, in the left and right banks at two fi xed depths, zone 1, depth 5–10
cm and zone 2, depth of 10–25 cm. Laboratory analyses included tests
of volume weight, specifi c weight, soil particle size distribution, consistent
states and humidity. Parameters porosity and clay activity were also
analysed. Soil sampling and laboratory testing were done in accordance
with SRPS.U.B1 geotechnical testing standards. The comparison of the obtained results was made between the banks and the gully bed, as well
as between the zones using tests: t-test of mean values; W (Mann-Whitney;
Wilcoxon) – median test. Hypothesis testing was performed with a
signifi cance threshold p of 95.0 %. Testing was conducted in the statistical
analysis program Statgraphics centurion XVIII (StatPoint Technologies, Inc.
2019). Comparison of soil parameters in zone 1 had shown a statistically
signifi cant diff erence for percentage of clay and sand, liquid limit, humidity
and clay activity. Results of conducted comparison showed that in
the zone 2, a statistically signifi cant diff erence found for the parameter
percentage of clay and sand, between banks and gully bed soil samples.
While no signifi cant statistical diff erence found for the other parameters.
Analysing the results between zones, a signifi cant statistical diff erence
was found for the gully bed, left and right banks soil samples for the
parameters volume weight (dry and humid) and porosity while for gully
samples there was signifi cant statistical diff erence for liquid limit, plastic
limit, humidity and clay activity. Comparing all samples of the zones 1 and
2, a signifi cant statistical diff erence was found for the parameters volume
weight (dry and humid), porosity, percentage of sand particles, plastic
limit and current humidity. | sr |
