PROPERTIES OF HUMUS SUBSTANCES IN DIFFERENTLY USED SOILS OF THE MILICZ-G£OGÓW DEPRESSION**

A b s t r a c t. This paper describes the fractional composition of humus substances and the physico-chemical and sorptive properties of Mollic Umbrisols Arenic, Mollic Gleysols Arenic and Phaeozems Arenic of the Milicz-G³ogow Depression. The following analyses were performed on collected soils samples: granulometric composition, pH in 1mol KCl dm -3 , hydrolytic acidity (Hh), TOC, Nt, CaCO3, content of exchangeable cations of alkaline character (Ca +2 , Mg +2 , K + , Na + ) and fractional composition of humus compounds using the Tiurin method. Loamy sand and sand dominate in granulometric composition. Reactions of the soils analyzed ranged from light acidic to alkaline. TOC and Nt content was highly differentiated, and values for the TOC/Nt ratio ranged from 7.9 to 26.9. Alkaline cations dominated in the sorptive complex. Base cations (S) were noted in the range 2.2 – 68.8 cmol(+) kg -1 , cation exchange capacity (CECt) in the range 2.8 to 69.4 cmol(+) kg -1 and base saturation (BS) was high, i.e. between 69.8 and 99.4%. In terms of the content of the fractional composition of the analyzed soils, a non-significant part was represented by the fraction Ia (fulvic fraction) which was in the range from 2.8 to 6.2% of TOC. Within humus matter, fraction I dominated (humic compounds bound with calcium and mobile forms of R2O3) (33.2 – 61.2% of TOC) and within it humic acid. The ratio of CHA:CFA reached the value of 1.1 – 4.2. CHA-Ca (humic acids bonded with Ca) share was placed in the range of 44.1 – 82.8% CHA, while Cpp (post-extraction residue) was in the range of 21.1 – 54.5% TOC.