This dissertation presents the results of the investigations of the impact of aggregate structure of mineral soils on their hydrophysical characteristics, i.e. water retaining capacity and coefficients of water transfer in saturated and unsaturated zones. Undertaken investigations comprised problems of methodological nature as well as fundamental model investigations and modelling, not only in the aspect of determination of optimum soil aggregation from the point of view of crop growing and yield, but also possibility of regulating the components of soil water balance, i.e. retention and evaporation and the factors directly influencing them, like conditions determining water movement in the soiL These were model investigations of the aggregates of different sizes selected from the arable layer of eight soils (podzols, brown soils, grey-brown podzolics, chemozems) from Lublin region. Obtained results indicated, that the investigations of hydrophysical characteristics of soils with aggregate structure should be performed on specially prepared soil material, and the parameters of soil aggregate structure determine their soil water properties in the following way:
- increase of soil aggregate sizes results in the decrease of their water resistance;
- size of soil aggregates differentiates water amount retained in the soil, especially in the range of soil water potentials referring to pF 0 - pF 2,2;
- increase of soil aggregate sizes caused the increase of the coefficients of water conductivity in saturated zone by two orders;
- increase of soil aggregate sizes caused the decrease of soil water conductivity coefficients in unsaturated zone by five orders;
- including the parameters of aggregate soil structure, as input data, into the model of soil water retention curves prediction, predominantly improved the accuracy of their estimation in the range of low soil water potentials.
It results from the above, that the knowledge of relation between aggregation of soils and their hydrophysical characteristics can be useful for choosing the type agrotechnical treatments for forming soil water properties.