Valery Vitalievich Demidov

The Department of Erosion and Soil Protection has developed the main scientific directions – «Assessment of ero- sion processes in soils of various bioclimatic zones», «Study of the basics of sustainable land use» and «Ecological and economic assessment of soil and land degradation». It is proposed to develop both existing areas of scientific research with a certain adjustment of their names and problems («Analysis and modeling of erosion processes in soils, including in the context of climate change», «Development of the concept of sustainable land use in the context of food security», «Ecology, economics and socio-demographic features of land use in the context of climate change and soil degradation»), as well as new directions that have some research history at the department — «Development of principles of soil protection», «Development of methodological foundations of land reclamation». The necessity of creating a holistic concept of soil protection is considered in particular detail. This concept should include both the formulation of legal (legislative and regulatory-methodological) principles of soil protection, and the definition of criteria for assessing soils under which their protection can be carried out, and the development of soil protection systems (first of all, from the manifestation of erosion processes) in various bioclimatic and administrative-territorial conditions.

Summary Soil erosion as one of the types of land degradation aff ects various economic interests of people. It is shown that the most promising areas of erosion studies, where economic methods can be applied, are — assessment of actual damage fr om soil erosion, determination of the magnitude of probable damage from the occurrence of erosion
processes in soils, economic analysis in the development of sustainable land use systems for territories whose soils are subject to erosion. Th e group of methods for determining economic damage is characterized by the greatest development, including taking into account ecosystem services that soils «lose» as a result of erosion processes. Methods for assessing the risk of soil erosion have signifi cant development potential, since by now a powerful database of predictive models and equations (USLE, RUSLE, RUSLE2, WEPP, EUROSE, CREAMS, EPIC, VNIIZiZPE, etc.) has been created, allowing to assess indicators of soil erosion in the future. Th e neoclassical theory of capital is used in the development of sustainable land use systems, which requires that the fertility of the soil and the net social benefits from non-market goods and services from agricultural land should be maintained over time. Th us, it is possible to
create compensatory taxation mechanisms for territories wh ere soil erosion processes occur.

The paper presents the results of assessing the eff ect of the degree of soil erodibility on the abundance and diversity of cultivated fungi and actinomycetes in diff erent seasons of the annual cycle. The objects of the study are sod—podzolic soils (Umbric Retisols (Abruptic)) of diff erent degrees of washout, located on the slope of the southeastern exposure (Moscow region, Solnechnogorsk district), used for a long time for the cultivation of agricultural crops. The indicators of microbial abundance were determined by the cup method, identifi cation was carried out on the basis of phenotypic characters. It is shown that the decline in physical and agrochemical parameters of the soil, which is a result of erosion processes, leads to a change in microbiological parameters. A decrease in the abundance and species diversity of fungi and actinomycetes was found with an increase in the degree of soil erosion. Significant diff erences were found in the taxonomic composition of microbial communities of non-eroded and washed away soils (the Sorensen species similarity coeffi cient does not exceed 0.42 for fungi and 0.30 for actinomycetes). Taxonomic units of mycelial microorganisms have been identifi ed. Among the fungi are representatives of the species Aspergillus, Cladosporium and Scopulariopsis, among the actinomycetes are Streptomyces malachitospinus, S. candidus and Micromonospora aurantiaca.

Kuznetsov’s formula relates the parameters of erosion resistance and soil water stability. However, the mechanism of occurrence of these properties is different: water stability is explained by the action of intra–aggregate hydrophobic bonds in organomineral soil gels, and erosion resistance is explained by water stable aggregates and their adhesion to each other. At the same time, the nature of the interaggregate bonds that ensure erosion resistance remains unclear. The purpose of the work was to clarify the mechanism of erosion resistance of soils and compare it with the mecha- nism of formation of water stability. The work used samples of humus-accumulative soil horizons: sod-podzolic and leached chernozem. To obtain samples with the same aggregate composition, but differing in erosion resistance, it is proposed to use soil polymer ameliorants (SPM). The erosion resistance of soils was determined on a hydrolotter and the critical rate of flushing was calculated. The water stability of the soils was assessed by the blade method. The particle size in the solutions was estimated by laser diffractometry. It was found that on soils treated with SPM, the results of the tray and blade methods correlate by 99%. The high correlation suggests a common nature of intra- and interaggregate bonds. To test the role of hydrophobic interactions in the formation of aggregates resistant to water, polymers of varying degrees of hydrophobicity were added to aqueous humate solutions in a model experiment: polyethylene glycol (PEG), polyacrylamide (PAA) and polyvinyl alcohol (PVA). In parallel, the water stability of soils treated with PEG, PAA and PVA was evaluated. The analysis of the results showed that the greatest water stability of the aggregates was noted when the most hydrophobic polymer, polyvinyl alcohol, was added to the soil, which formed the largest particles when interacting with humate in the model experiment. These results confirm the role of hydrophobic interactions in the formation of aggregates and indicate that when selecting polymer structures, their interaction should be taken into account not with clay minerals, but with soil gels, which include clay minerals and humic substances.