HUMIC ACIDS OPTICAL PROPERTIES OF RENDZINA SOILS IN DIVERSE ENVIRONMENTAL CONDITIONS OF SERBIA

Abstract

This study examined the impact of climate, altitude and landforms on humic acids (HA) optical
properties (E4/E6, ΔlogK, RF indexes) in Serbian Rendzina soils. HA humification degree of calcareous
and decarbonated Rendzinas under natural vegetation (forest and grassland, separately) decreased with
altitude increasing. This particular rule was not manifested in arable Rendzinas. HA humification
degree in Rendzinas on flat positions (hilltop and footslope) is significantly higher than in Rendzinas on
slope sides. Humification degree of HA is the highest in Rendzinas in eastern Serbia (in the vicinity of
Negotin), followed by central Serbia (Sumadija) and Srem, southeast and finally, southeast and
southwest Serbia. With respect to the climate change foreseen for the end of this century, i.e. increase of
precipitation and temperature variance among the regions in Serbia, also an increase in variance of
quality of humic acids in Rendzinas on different altitudes and regions can be expected.