A methodical approach to the digital mapping of the arable lands area depending on their soil-agroecological and positional conditions is proposed. The approach was tested on a model plot located on the Valdai Upland with an area of 160 thousand ha. Small-scale agricultural development of the poorly dissected moraine plains is limited by the wide distribution of overmoistened soils. Using the traditional discriminant analysis, a measure of the topographically determined duration of soil overmoistening was calculated based on a comparison of the morphological diagnostics of water regime and topography runoff properties according to the grid elements of 30 × 30 m. The drainability range was determined for the arable lands of XVIII century, reconstructed according to the materials of the General Survey. This allowed us to determine the potential area of the arable lands for this period. The area of arable lands, which is characterized by favorable conditions of transport accessibility and soil drainability, was 12 %. At the same time, reconstructed area contained 5 %. In the subsistence economy of the XVIII century more than a half of the potential arable lands of the model region turned out to be undeveloped.

Results of 24 soil monoliths studying in the collection of Dokuchaev Central Soil Museum were analyzed in terms of diagnostic criteria in Russian soil classification system; these were chestnut, brown aridic, pale and cryoaridic soils. The topsoils of chestnut and brown aridic soils meet the criteria for the light-humus horizon (AJ), but their values in Munsell readings proved to be lower. In pale soils, the upper horizons were identified as gray-humus instead of light-humus ones as prescribed in the system. The cryohumus AK horizon, diagnostic for cryoaridic soils, is peculiar by the abundance of reddish frost-fragmented plant residues (detritus). We failed to differentiate metamorphic BM and xerometamorphic BMK horizon, they had more features of the latter. Both horizons are similar to the pale-metamorphic BPL horizon in color, although the BPL has a definitely weaker structure displaying some cryogenic features. These are less prominent in cryoaridic soils than in pale soils, hence, the diagnostic BPL horizon in cryoaridic soils may be removed to the category of diagnostic property. A similar re-evaluation may be proposed for the carbonate-textural CAT horizon: to consider it as a diagnostic property in the carbonate-accumulative horizon (ВСАt). The ВСА horizon in all soils studied differed by carbonate pedofeatures, namely, segregations in brown and chestnut soils, impregnations in pale soils, impregnations and coatings in cryoaridic soils.

Understanding the variability of acidic properties in the soil cover of floodplains is of greatest importance as far as it helps to ensure the rational management of floodplain areas, since the pH level is a fundamental indicator that determines the concentration of soluble and available elements for plants. This article provides the results of actual, potential and exchangeable acidity measurements performed in 87 soil profiles located within the upper and middle reaches of the Amur River. Descriptive statistics, correlation and linear regression were used to characterize acidity. It has been established that acidity decreases in the floodplain of the upper and middle reaches of the Amur River in the following direction: alluvial marsh (peat-gley and humus-gley) soils, residually-alluvial (rzhavozems and brunezems) soils, alluvial gray gley soil, alluvial gray humus. The soils of the upper Amur floodplain are more acidic in comparison with the soils of the middle Amur, the average pH_KCl values in soils with the same genesis of the former are less by 0.2–0.4 than the ones of the latter. It was revealed that the regression coefficient is indicative of the acid-base functional groups of the soil components which are in charge of soil pH. The coefficient greater than 1 points to the organic nature of acidity; below 1 – to the prevalence of mineral acids.

The dynamics of the organic matter of the chronosequence of sod-podzolic soils in the process of reforestation has been investigated using the granulo-densitometric fractionation.The objects of research were sod-podzolic soils of the chronosequence of abandoned areas, including the main stages of the development of secondary succession: from overgrowing by grass vegetation to zonal spruce forests of the specially protected natural territory of the Central Forest State Natural Biosphere Reserve. In the first 20–25 years after the reduction of agrocenosis, degradation changes of the humus state of sod-podzolic soils were observed, due to the lack of agrotechnological treatments and the lack of fresh organic matter (OM) of cultivated plants. It is shown that only after 50 years functioning in the reservoir regime, the qualitative and quantitative indicators of organic matter of sod-podzolic soils begin to approach those of spruce forests of different species composition over 100 years old. This is manifested in an increase in the amount of discrete OM, the level of carbon accumulation of this fraction of OM in the soil and the value of its share in the total carbon accumulation in the soil.

During the model experiment the changes in the mineralogical composition of the open surface of arable soil (leached chernozem, gray forest soil, sod-podzolic soil) under the impact of raindrops under fallow conditions were studied. At the end of the experiment a mineralogical analysis of individual particle size fractions < 1, 1–5, 5–10 and > 10 μm from microcrusts formed on open surfaces and a soil substrate not exposed to the effects of precipitation was conducted. The study found that during the exposure there was redistribution and changes in the proportional ratios of the contents of different particle size fractions and associated clay and clastogenic minerals. During the experiment the most significant changes due to their composition occurred in the sample of sod-podzolic soil and leached chernozem. The content of clay minerals in exposed samples decreased the most. The redistribution of clastogenic minerals from the upper open layer, mostly from fine silt and to a lesser extent from the middle silty fraction, was accompanied by a relative accumulation of the fraction > 10 μm. The redistribution of granulometric fractions was accompanied by a relative accumulation of quartz, orthoclases and a decrease in the content of chlorite and biotide in them. Such a distribution is determined by their resistance to weathering. Balance calculations allowed establishing that the total losses of clay and clastogenic minerals from the upper open surface of the monoliths in comparison with the initial soil substrate were more than 4 kg / 100 kg of monolith for gray forest soil, 16 kg / 100 kg of monolith for leached chernozem and 46 kg / 100 kg of monolith for sod-podzolic soil.

When setting a long-term field experiment in order to study the impact of direct sowing technology on soil properties it is necessary to take into account not only the known requirements, but a comprehensive analysis of soil heterogeneity as well. The article presents the results of detailed topographic and soil-agrochemical mapping with estimation of variability of morphological and agrochemical properties of typical chernozems studied on four experimental fields of 2.4 ha area each.

The main results of studying the effect of artificial woody vegetation on chernozem are briefly described in the article, as well as the influence of soil and soil condition on composition and productivity of forest plantations. The effect of soil salinity on plant growth is characterized. The toxicity of different groups of readily soluble salts, especially chlorides and soda, has been evaluated. The decisive role of the depth of toxic amounts of chlorides and the level of water availability in the soil usability has been established. The ecological series of water availability for plants in different soil types have been developed and the degree of suitability of groundwater of different salinity has been evaluated. The power of the root zone as a limiting factor has been estimated, as far as the level of mineral elements supply for plant nutrition (trophicity) in the soil is determined by the greatest total amounts of phosphorus and potassium in the root zone (excluding potassium enclosed in feldspar lattices). All the intrazonal diversity of nature is due to the nutrient status and moisture content in the soil. Along with the warmth level these limiting resources develop one or another level of soil fertility. The role of subsurface runoff in the formation of forest-steppe landscapes is characterized. The stages and phases of the primary soil-forming process are highlighted. It is argued that soil zonality results from bioinert nature of the soil. The article substantiates the statement that soil fertility is a factor ensuring the stability of life on Earth; and the ways of promoting Soil Science at the level of the theoretical basis for agriculture have been proposed.

The implementation of the “4 per mille” or “4 per 1000” Initiative in Russia can be one of the instruments mitigating concentration of the greenhouse gases in the atmosphere. It is estimated that the total annual absorption of carbon dioxide (CO₂), including natural dynamics and application of carbon saving technologies in agriculture, can be as much as 23–28 % of annual emission of the gas into the atmosphere. The “4 per 1000” Initiative mechanism will operate successfully for 12–15 years, which corresponds to the time of saturation of arable soil with carbon. The implementation of the “4 per mille” Initiative is not only Russia's positioning among the countries that support sustainable, energy-efficient and environmentally friendly development, but also demonstrates the ability of the country to realize its competitive advantages in demand in the low-carbon world.