The decomposition of natural and synthetic polymeric materials (peat, humates, biochar, strongly swelling hydrogels and other soil conditioners) in a biologically and chemically active soil environment inevitably leads to a reduced ability to improve the structure, water-retention, absorptive capacity and fertility of artificial soil constructions in urbanized ecosystems and agro landscapes (constructozems). Quantitative assessment of the biodegradation process using field and laboratory incubation experiments, as well as mathematical modeling, showed the possibility of significant (up to 30–50% per year) losses of organic matter of constructozems and a corresponding deterioration of soil quality. Incubation experiments that track the carbon dioxide emission rates of polymeric materials under given thermodynamic conditions allow for the estimation of decomposition rates in addition to an exploration on the dependence of such rates on additions of microbial inhibitors. The use of nomographs provide an opportunity to optimize long-term amendment performance in soil constructions by identifying the most favorable depths to apply amendments to ensure stable functioning during desired in-service timelines in the built environment. The results of the study are useful for geo-engineers and landscaping practitioners.

The ecological status and functioning of soils in urban ecosystems are considered. A series of criteria and simple methods of their determination are suggested to assess soil suitability for landscaping purposes. Their practical application is shown by the example of the ecological assessment and monitoring survey of different urban territories in the southwestern, western, and northwestern administrative districts of Moscow and in Moscow suburbs. It is shown that the main damage to the soils of actively used territories in Moscow is due to the artificial salinization induced by the application of deicing substances and fertilizers. The second factor of soil degradation is the soil compaction. An unfavorable water and air regime (a deficit or excess of soil moisture) is a factor that manifests itself sporadically in time (during the extremely dry years) and in space (at the sites with an increased soil compaction and soil water evaporation). A considerable decrease in the potential biological activity of urban soils, including the soils of newly built residential areas, in comparison with their natural analogues attests to the disturbance of their functioning under the impact of chemical pollution and an unfavorable physical status.

On the basis of thermodynamic concept on competitive interphase interactions, the idea is forwarded about the ionic-electrostatic mechanism of water retention capacity and aggregative stability of...

Numerous experimental data obtained by different methods confirm the theoretical ideas about the electric nature of the interaction between the solid and liquid soil phases, which were first suggested by the Maxwell-Boltzmann-Helmholtz-Gouy and Deryagin-Landau-Verwey-Overbeek theories about the double electric layer in two-phase disperse systems. The interaction between the solid phase and water in the diffuse part of this layer may be described by the theoretically derived equation lnP _w = A − BW, where P _w is the soil moisture pressure, W is the ratio between the masses of the water and the solid phase in the soil, and A and B are physically grounded parameters. The exponential form of this equation first predicted by the out-standing researcher Gouy 100 years ago results from the exponential distribution of ions in the diffuse layer near the electrically charged surface of the solid soil phase.

A new instrumental method was proposed for the rapid estimation of the water-retention capacity of soils and sediments. The method is based on the use of a centrifugal field to remove water from distributed soil columns. In distinction from the classical method of high columns, the use of a centrifugal force field stronger than the gravity field allowed reducing the height of the soil samples from several meters to 10–20 cm (the typical size of centrifuge bags). In distinction from equilibrium centrifugation, the proposed method obtained an almost continuous water retention curve during the rotation of the soil column only at one-two centrifuge speeds. The procedure was simple in use, had high accuracy, and obtained reliable relationships between the capillary-sorption water potential and the soil water content in a wide range from the total water capacity to the wilting point.