Evolution of the soil humus status on the calcareous Neogene clay dumps of the Sokolov quarry complex in the Czech Republic

The development of the soil profile and the humus substance system was described for two chronosequences of soil restoration on the Neogene clay dumps. The chronosequences differed in the restoration type of vegetation: self-overgrowing or overgrowing intensified by planting tree seedlings (rehabilitation). It was found that the regeneration rates of the soil and humus profile were much higher in the case of the land rehabilitation than during the self-overgrowing of the dumps. The acceleration of the ecogenetic succession and the symbiotic nitrogen fixation in the soils of the plots with seedlings planted resulted in the accumulation of humus and nitrogen and increased the degree of organic matter humification. The enrichment of the organic matter in nitrogen and its increased input were the main reasons for the more intense humification under the rehabilitation conditions.