| dc.description.abstract | This study aimed to analyze properties of the soil formed on amorphous material. Pyroclastic rocks were recognized and mapped on the Geological Map of SFR Yugoslavia in the scale 1:100 000. Investigated soil profile is located northeast from Vujan mountain (43° 58’ 21.8’’ N, 20° 29’ 58.4’’ E, 667 m a.s.l.) on a hilly forest terrain with mild slope.
Soil profile depth was 61 cm and it was differentiated into O - horizon (0-3 cm), A – horizon (3-17 cm), AC – intermediate horizon (17-23 cm) and C - horizon (23-61cm) horizon. Parent material was recognized as a weathered tuff.
Active and exchangeable acidity were measured by pH meter. Presence of amorphous material was tested using method of Fieldes of Perrott (pH in NaF). Organic matter content was determined by Tjurin method, and particle size analysis by sedimentation and pipette method. Bulk density was determined using cylinders and specific gravity by picnometer while phosphate retention was determined by New Zealand method.
Mineral composition was determined by XRD analysis on Philips PW1051 diffractometer, under following conditions: U = 36 kV; I = 18 mA; velocity 10/ min; Rc = 4/2. XRD analysis was performed on air-dry; ethylene-glycol saturated and heated (550°С) samples of surface horizon (A horizon) and of parent material (C horizon).
Reaction in water suspension (1:2.5) was extremely acid (3.8 to 4.1). Test with 1M NaF gave values from 8.2 to 8.8. A NaF pH of 8.4 or more indicates a significant component of short-range-order minerals in the exchange complex. Organic matter content was 5.1% in A horizon and 1.4% in AC horizon. Phosphate retention decreased with depth, from 51% to 38%.
Specific gravity of soil particles ranged from 2.26 gcm-3, in surface horizon, to 2.38 gcm-3 in parent material, while the bulk density of surface horizon was 0.88 gcm-3. Particle size analysis showed indicated uniform texture along the soil profile. Silt size fraction prevailed in soil, and it slightly increased with depth, from 80.1% to 84.4%. The studied soil had silt loam texture.
Mineral analysis of the surface horizon revealed presence of quartz, biotite, vermiculite, feldspars, etc. Diffractograms of the parent material indicated presence of quartz, lepidomelane, vermiculite, biotite, etc. Diffractograms of samples from surface horizon and parent material showed background from 2 to 6 Å, which is indicative of amorphous material.
The analyses have revealed some andic properties of this soil. | sr |
