Physics of soils annual, seasonal, and daily dynamics of water balance elements in soddy-podzolic soils

摘要

The vertical flow in automorphic soils is formed under the effect of many factors throughout the year. They may conventionally be classified into two large groups: soil factors, including the structure and properties of the soil profile; agronomic;and biological factors and meteorological factors, primarily precipitation and air temperature. The complex and heterogeneous structure of soil cover in natural conditions and the variability of weather conditions do not allow these groups to be clearlydistinguished. Therefore, it is difficult to indicate the determining factor in a specific case. This is an important problem, because the soil moisture, on one hand, is an essential soil component and its amount determines all soil functions, and, on the other hand, it serves as a carrier of substances removed beyond the soil profile. In the study of soil water regime, the main attention is given to moisture movement during the vegetation period, and the problem of subsurface flow formation during thespring snowmelt and fall freezing frequently remains beyond the scope of studies. In these periods, moisture passes from the liquid to the solid phase and vice versa. In addition, the presence of a layer with negative temperatures, whose thickness variesin time, probably affects the infiltration rate even within a day. The lysimetric method is widely used in soil science for studying the vertical movement of soil moisture and substances. Soil in lysimeters serves as a one-dimensional physical model ofsoil cover, and all lysimetric units are designed in some measure for data acquisition on the permeability of separate horizons or the whole soil profile. The aim of this work was to study the formation of lysimeter runoff as depending on weater conditions, soil profile properties, and the biological factor (presence or absence of plant cover). The following tasks were set: (1) to examine the features of hydrological seasons in an annual cycle on the basis of lysimeter runoff; (2) to study the soil water regime in the spring, summer, and fall periods in different surface conditions (plant cover and precipitation of varying intensity); and (3) to study the water regime and soil water pressure in soil profiles with different structures.