Impact of land use on water properties of rendzinas

The human agricultural activity leads to very strong changes in the soil - even the period of several decades of fallowing as well as the restitution of potential vegetation communities are not able to level those transformations. The climatic changes and agricultural use discontinuation from calcareous soils are caused to coining into existence the climax forest communications oil these areas. Rendzinas that were agriculturally used in the past, despite the development of secondary xerothermic swards differ in their hydrophysical properties from the soils occupied by the primary swards. In this work the impact of the way of land use and the natural successive transformations of vegetation on the hydrophysical properties of rendzinas were shown. The surface horizons of cultivated and fallow rendzinas (in comparison with the respective horizons of soils overgrown by primary xerothermic vegetation) are characterized by greater bulk density, lower water retention in the full range of the studied soil water potentials, smaller number of pores, especially of the large pores (dia > 18.5 mu m). Water retention and conductivity for soil water potential > 1 hPa of surface horizons of fallow rendzinas are close to the values that are characteristic for soils overgrown by shrubs, this being a possible cause of the instability of secondary xerothermic swards as well as of the fast rate of succession in the direction of shrub and forest communities.