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ŠUMARSKI LIST 9-10/2017 str. 20     <-- 20 -->        PDF

Field sampling and laboratory analyses Uzimanje uzoraka na terenu i laboratorijska analiza
The investigations were carried out within a catchment in there different adjacent LUTLC namely, natural forest (scots pine forest), grassland, and cultivated land (dry farming) at two aspects apart: one on a north – facing slope and one on a one on a south – facing slope. The distributions of sampling plots in the grid system (50 x 50 m) are total 180 soil samples (3 land use types x 2 aspect facing slopes x 30 surface soil samples) for all three different adjacent LUTLC at two aspects (north – south). Soil samples were collected at surface soil (0 – 30 cm depth) (because of effective depth of soil organic matter accumulation in the study areas). The undisturbed soil samples were taken by a steel core sampler of a 100 cm3 volume for dry bulk density analysis (180 samples) and 400 cm3 volume for saturated hydraulic conductivity analysis (180 samples).
Particle size distribution was determined by the hydrometer method (Bouyoucos, 1951). A wet sieving method was used to determine the coarse fragments and water stable aggregates (WSA) (Kemper and Rosenau, 1986). Soil water retention field capacity (FC), wilting point (WP) and available water capacity (AWC) at 0.33 and 15 bar tension were determined using a pressure plate (Blake and Hartge, 1986). Dry bulk density (BD) was calculated by dividing the oven dry mass at 105°C by the volume of the core (Cassel and Nielsen, 1986). Saturated hydraulic conductivity (Ks) were determined by the core method (Cassel and Nielsen, 1986). Soil pH and electrical conductivity (EC) were measured on a 1:5 soil to water ratio suspensions by a pH/conductivity meter (Rhoades, 1996). Total nitrogen (TN) was determined by Kjeldahl method (Bremner, 1996). Carbonate (CaCO3) was determined by pressure calcimeter method (Richard and Donald, 1996). The concentration of soil organic matter (SOM) was determined by using the Walkley and Black method (Nelson and Sommers, 1996). The soil infiltration rates were measured at each sampling point of three LUTLC using tension disc infiltrometer (Perroux and White, 1988) as described by Moret and Arrúe (2007) for structured soils and by Ankeny et al. (1988) and Reynolds and Elrick (1991) for other soils. The measurements with tension infiltrometer were made in summer, and conducted on a total of eighteen sample plots: principally distributed in three replicates on three different LUTLC with north and south facing slopes.
All data were analyzed using SPSS® 20.0 (IBM corporation software) statistical software. Analysis of variance (ANOVA) was used to detect the significant differences in the measured variables (p < 0.01 and p < 0.05) among land use types or between north and sought aspects. Differences among means of LUTLC and between north and south aspects were considered significant at the p < 0.01 and p < 0.05 level using the least standard difference (LSD) multiple comparisons test.