The objective of the present paper is to contribute to the evaluation of quantity and quality of non-humified part of soil organic matter (SoM). in samples of soil organic matter from the humus profile of Šumava forest soils and forest meadows, taxonomically designated as mor and moder forms, the fractions of labile soil carbon C cws , C hws , C PM and fraction of stable carbon represented by carbon of humus acids C Ha and C Fa were determined. organic matter of samples was fractionated according to the degrees of hydrolyzability by two different methods in particle-size fractions of 2.00-0.25 mm and < 0.25 mm. The quality of labile fraction C hws was expressed on the basis of reaction kinetics as the rate constant of biochemical oxidation K bio and rate constant of chemical oxidation K chem of the first order reaction from a reduction in the concentration of C-compounds. The highest values of labile forms of carbon were determined in samples with the least favorable conditions for transformation processes of SoM, and these samples also had the highest content of labile forms in hydrolyses by both methods and the most labile fractions at the same time. The degree of SoM humification was strictly indirectly proportional to the lability of SoM and its hydrolyzability. The quality of labile fraction C hws can be expressed by both K bio and K chem while the sensitivity of K bio is higher but the reproducibility of K chem is better. K bio corresponds with the degree of SoM transformation, K chem with the proportion of C PM in total C ox .

Changes of soil phosphorus parameters (SPP) and soil organic matter (SOM) fractions were investigated in a Cambisol of medium-heavy texture. Soil sequential samples were taken from a minimum (MT) and conventional (CT) tillage field in Sitzenhof (Germany). For the CT soil, concentrations of available forms phosphorus (P) were stable to ,0.3-m depth, below which they rapidly decreased to relatively low values. In contrast, the decrease in the MT soil profile was gradual from the surface layer; available forms of P concentrations were higher and sorption index values were lower than in the CT soil in corresponding depths. Concentrations of SOM fractions were higher in the MT than CT treatment soil along the whole soil profile, especially below the 0.3-m depth. The correlations between SPP and SOM fraction concentrations were closer in the MT than in the CT, particularly below 0.3-m depths.

Quantitative and qualitative soil organic matter properties were observed in a specific large area experiment (Chernozem &ndash; Gross Enzersdorf, Austria) and in a medium-term field experiment (Cambisol &ndash; Studena, Czech Republic). Two technologies &ndash; minimum tillage (MT) and conventional tillage (CT) &ndash; were compared by means of the determination of quantitative and qualitative soil organic matter parameters of the soil samples in the years 2004&ndash;2005. Cambisol showed higher values of quantitative soil organic matter parameters in MT compared to those in CT over the whole soil profile. For Cambisol, the qualitative parameters were almost comparable for both technologies. Chernozem showed more favourable values of the quantitative parameters in the surface layer in MT, however, the values had rather a contrary trend in deeper soil layers. CT showed slightly more favourable values of the qualitative soil organic matter parameters in Chernozem. It can be said that Chernozem organic matter reaction to tillage technology changes is slower and of minor rate in comparison with that of Cambisol organic matter. The results of quantitative and qualitative parameters do not conform with the generally recognised values for the Chernozem soil type.

Changes of soil organic matter (SOM) parameters were investigated in a haplic Luvisol with medium-heavy texture. Soil samples were taken from several layers at minimum (MT) and conventional (CT) tillage plots of a field experiment in Sitzenhof (Germany). All cultural practices except for tillage (crop rotation, fertilizing, protection measures, etc.) were identical over the whole time of the experiment. The concentrations of oxidizable carbon C ox and its constituents (humic acids (HA), fulvic acids (FA), and hot-water soluble carbon) are comparable in layers 15-20 cm in both variants. In 0-15 cm and 30-55 cm layers, these concentrations were higher in the MT variant. A similar trend was observed in the colour quotient values of humic substances Q4/6, which indicates increasing condensation of humus substances (HS) at deeper layers in both variants, and it is also confirmed by a humic to fulvic acids ratio HA:FA. Concentrations of SOM fractions were higher (except 15-20 cm layers) in the MT than CT treatment throughout the profile, especially below the 30 cm depth. The SOM did not accumulate markedly in the surface layer of long-term MT treatment.

For the purposes of assessment of long-term changes, two sets of Chernozems soil samples were analysed and compared in parallel: ‘old’ file samples obtained during the Soil Survey 1960–1970 in the former Czechoslovakia and a ‘present’ (2013) set of samples from exactly the same sites as the archive samples. The recently collected samples revealed worse qualitative parameters (lower humic acid to fulvic acid (HA/FA) ratios and higher colour quotient Q4/6 values) than the file samples, for all the localities. On the other side, the quantitative soil organic matter (SOM) parameters (oxidizable carbon (C_ox) and all its determined components) showed contrary results. The amount of total SOM at the same sites is higher now than it was about 50 years ago. It can be concluded that the current decline in SOM quality in Chernozems is partly compensated for by higher accumulation of SOM in the soils. All the analysed Chernozem samples were found to have much worse qualitative SOM parameters than the values mentioned for this soil type in the older literature. However, a comparison of the current data and the file data of Chernozem SOM quality can still be considered an open issue and require more complex research.