abstract:      The study was carried out on 14 muck soils at different state of secondary transformation. The soils were characterized by the water holding capacity index, This index describes the state of the mucking process. The main purpose of the research was to examine the relations between some bio-physico-chemical properties and the stage of secondary transformation.
     The study was also to adapt the humification number as an index of the state of secondary transformation of organic soils in comparison of the water holding capacity index. The relationship between W1 and the humification number Hz was found. The obtained results indicate that the simultaneously using both indexes give better characteristic of the state of secondary transformation of organic soils.
     The method applied in this paper are useful to investigation of the degree of secondary transformation.
     Nitrogen adsorption, water vapour sorption and desorption were investigated. From the experimental results the specific surface area values, adsorption energy and fractal dimensions were calculated. The existence of a relationship between surface area determined from water vapour desorption data and water holding capacity index which characterizes the state of secondary transformation of the peat was proved. The relationships between the specific surface areas determined from water vapour and nitrogen adsorption data, and some important physical properties e.g. ash content, bulk density and total porosity of studied mucks were found.
     Potentiometric titration was used for obtaining detailed information on acid-base properties of mucks. From titration curves the variable surface charge and apparent surface dissociation constants were calculated. The results obtained allow to state that studied mucks have different quantitative and qualitative characteristics of surface functional groups.
     Process of secondary transformation influenced the soil environment for the microbes by changing the physicochemical properties. This way it influenced the number of microorganisms and caused changes of biological activity in the soils.