Patterns of profile variability of drained peat soil properties

Abstract

Actuality. The problems of efficient use of drained peat soils are increasingly becoming the focus for meliorators, ecologists and the public in Ukraine. The purpose of the article is the publication of new knowledge on the patterns and mechanism of transformation of physical and water-physical properties of peat soils using new methods of laboratory research that will promote harmonization of productive and ecological functions of drained peatlands.

Research methodology. The research was carried out using six samples of peat soil with unchanged structure, selected from different depths of two soil profiles in the territory of Sarny experimental station. The hydrophysical studies of moisture-holding capacity of samples were conducted using a radial scheme in accordance with the requirements of DSTU ISO 11274. The test algorithm was as follows: saturation of the sample to maximum moisture capacity under vacuum, rapid desorption, equilibrium sorption and re-desorption, determination of the final soil moisture and density, calculations and construction of graphs. The innovation of laboratory research is the determination of a capillary hysteresis loop of moisture-holding capacity, characteristics of peat pore space structure and the calculation of the values ​​of field moisture-holding capacity according to the normalized descriptive kinetic graph.

Results. The quantitative patterns of density decrease with the depth and a rise of maximum moisture-holding capacity (MWHC) and field moisture-holding capacity (FMHC) are established. The values of these parameters for the arable layer are significantly different from the properties of deep horizons. The patterns of the profile variability of parameters are identical for both soil profiles. The most informative indicator was the structure of the pore space of peat soils.

A comparative analysis of the porous space structure of different soil layers suggests that the transformation in soil density and water-physical parameters of MWHC and FMHC in the arable layer occurs due to a decrease in the total pore volume, when the size of the pores is smaller than r <2.5×10^-3cm, which are located preferably in undecayed plant residues in accordance with the model of double porosity of peat.

The structure of the pore space of the arable layer indicates the presence of the processes of secondary epigenetic self-organization of decayed organic mass with the formation of the structural macroporosity of the peat soil, which can be purposefully controlled.