Thermophysical Properties of Chernozem Soils Growing Ornamental Plants in Summer

Abstract

Currently, there is no data on the transfer of heat and moisture of arboretum soils that grow such ornamental plants as Meyer lilac (Syringa meyeri), rowan “Alaya” (Sorbus aucuparia), and dwarf thuja “Danica” (Thuja occidentals). We experimentally determined that the thermophysical qualities of chernozems in lilac plantations changed with the water regime in the growing season. The sample maximum values of volumetric heat capacity and thermal conductivity were observed in the dense illuvial horizon. The sample minimums were registered in the AB transition horizon. Thermal diffusivity was the highest at the lowest humidity. In rowan plantations, the moisture content in transitional and illuvial horizons AB and B changed insignificantly. Such moisture distribution corresponds to the slope aspect and the features of rowan. The thermophysical coefficients also slightly fluctuated in rowan plantations, especially in the underlying horizons AB and B. The same horizons displayed the sample maximum of thermal diffusivity. It corresponded to the moisture content of capillarity disruption (MCCD from now onward). MCCD is a value lying between the minimal water potential of soil and the Briggs-Shantz wilting coefficient. It denotes the water content, at which moisture mobility and conductivity sharply decrease. In thuja plantations, the indexes of volumetric heat capacity and thermal conductivity in the upper soil horizon were minimal. In the illuvial horizon, these indexes were 42% and 12% higher, respectively. However, the uniform distribution of moisture in the soils that grow thuja has equalized thermal diffusivity in the AB and B horizons. Overall, the soil profile of rowan plantations contained less moisture than that of lilac and thuja plantations. Therefore, the volumetric heat capacity and thermal conductivity were lower, since they corresponded to the soil moisture content.