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Humid conditions do not encourage the formation of salt-affected soils enhancing leaching salts out of soil profiles. Nevertheless, the occurrence of salt-affected soils under humid climate is evident as a result from another factors but not the climatic one. Soil salinity in these landscapes is caused by anthropogenic salinization. The objective of this study was to identify types of chemical composition and salinity level of soils forming within the impact zone of artesian water discharge. This paper also provides determining the degree of contrast to adjacent non-saline soils and salt contamination boundaries. Soil and water samples were collected from three sites located in the Yaroslavl’ region, the Upper Volga. Sampling was released in June 2017. In the Upper Volga region high-mineralized water rises from saline aquifers via abandoned exploration wells drilled in the 1960s. These soils are found under an average annual rainfall of about 500-700 mm in taiga zone. This type of climate and vegetation cover normally should lead to the formation of Albic Retisols. Saline waters affecting soils are dominantly Na-Cl or Ca-Na-Cl-SO4 brines. Total dissolved solids in the saline waters range from 10000 to 259500 mg·L-1. Salt-affected soils have from low to high salinity (0,1-0,8%) but salt content does not exceed 1%. In the study areas maximum of salinity in the soils investigated was fixed near the water table or was associated with lithic discontinuity or abrupt textural change. Salt leaching from the upper horizons prevails in the course of annual cycle and that is what differs them from hydromorphic saline soils formed in arid climate. Field electrical surveys of salinity indicated the local zones of salinization. The salinization phenomenon in humid climate is not of the main pedogenic processes but the additional process. The upper horizons of salt-affected soils tend to have similar morphological features to zonal and intrazonal soils. The salt-affected soils studied were classified according to WRB as Orthofluvic Fluvisol (Humic, Loamic, Endosalic, Technic), Orthofluvic Gleyic Fluvisol (Humic, Siltic, Endosalic, Raptic), Amphistagnic Albic Retisol (Siltic, Anoaric, Cutanic, Endosalic), Albic Retisol (Siltic, Anoaric, Cutanic, Endosalic, Raptic).

The purpose of this work was to characterize the postagrogenic transformation of soil organic matter (SOM). For decision of this purpose the results of chemodestructive fractionation (CDF), the content of chlorophylls a and b , pheophetins and carotenoids, and Margalef's pigment index (PI) were used newly. Subjects of inquiry-humus horizons of soils of arable lands and fallow areas of Poshekhonsky district of the Yaroslavl region of the Russian Federation-were stitch together into two groups with differ in the type of land use. In one of them, the soils remained arable for 30-40 years (arable-arable group), in the other - the soils of arable land for the same time period were transferred to the fallow (arable-fallow group). It was found that increasing the soil water content of fallow plots compared to arable soils can lead: to improved livelihoods of the soil algocenoses (the value of PI Margalef decreased) to increase the carbon content of organic compounds, to increase the number legkomyslenno fraction in the organic component of soil, increased hydrolytic processes that reduce the content of carotenoids and chlorins (in particular, pheophytinand chlorophylls a and b) in SOM composition. Thus, results of CDF and content of chlorophylls a and b , pheophetins and carotenoids can be used to assess the postagrogenic transformation of SOM, and Margalef's PI-to characterize soil algocenosis.

The assessment of the agricultural production potential of the soils of the former arable lands was carried out on the basis of the updated soil-ecological index. It was revealed that among the agrosoils of Poshekhonsk district, soils with 20-39 points prevail, which generally indicates low and medium levels of potential soil fertility in the studied area in the late perestroika period. Comparison of morphological and genetic properties of soils for the period 1988-1990 and for 2019 showed the trends of their evolutionary changes. Multidirectional trends in the transformation of soil properties, developed on a contrasting lithogenic parent rocks, with a change in land use during the last 30-35-year period have been established. In loamy soils, stable hydromorphism features are observed everywhere, degradation processes prevail, expressed in dehumification, a sharp depletion of mobile forms of mineral nutrition elements of plants and, in some cases, acidification of humus postagrogenic horizons. It has been established that fallow soils on loamy parent material are characterized by a noticeable (by 1.1-1.9 times) decrease in the values of soil-ecological index in comparison with their arable state. On the contrary, in soils of light particle size distribution, the dominant processes are due to an increase in humus content and a decrease in acidity. The specificity of postagrogenic evolution and the emergence of new soil properties should be taken into account when performing soil-agroecological assessments and forecasting agricultural production potential against the background of changed climatic conditions.