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The study presents the results of using geo-information systems and neuro-technologies for modeling spatial heterogeneity and forecasting changes in agro-chemical properties of steppe soil fertility exemplified by Kherson region of Ukraine. Modeling allowed determining general regularities of impacts of the current agricultural practices on changes in the content of macronutrients over the past 50 years that have caused the ongoing process of a gradual decrease in the content of humus, nitrogen, phosphorus and potassium in steppe soils. A lack of balanced crop rotations, regular, uniform and necessary supply of fertilizers, occurrence of water erosion, including irrigation erosion and deflation, and also long-term irrigation led to a drop in the content of macronutrients in 1970-2020: the content of humus - by 0.36% (from 2.56% to 2.20%) or by 14.1% in statistical relation; mobile phosphorus - by 34.2% (from 62.0 mg·kg-1 to 40.8 mg·kg-1); exchangeable potassium - by 17.8% (from 442.4 mg·kg-1 to 363.8 mg·kg-1); a decrease in the content of nitrifiable nitrogen - by 17.0% (from 23.0 mg·kg-1 to 19.1 mg·kg-1) on the average in 2013-2020. Geo-statistical analysis made it possible to determine spatial regularities of changes in the content of macronutrients in steppe soils. The method of autocorrelation analysis was used to measure the minimum and maximum radii of typicality of the formation of agro-chemical properties of steppe soils being from 2.5 to 12.5 km, respectively. It indicates considerable spatial heterogeneity in distribution of macronutrients within the contours of different soil types. The neuro-technological modeling resulted in the creation of three-layer artificial neural networks for space-time modeling of the content of macronutrients in steppe soils. The reliability of approximation of neuro-models on test samples equaled 92.4-94.8%. An irreversible process of gradual depletion of steppe soils is forecasted under the current agricultural practices: a drop in the content of humus - by 0.01% per year on non-irrigated lands, by 0.03% per year on the average on irrigated lands; nitrifiable nitrogen - by 0.04 mg·kg-1 of soil on non-irrigated lands, by 0.06 mg·kg-1 of soil per year on the average on irrigated lands; mobile phosphorus - by 0.16 mg·kg-1 of soil per year on non-irrigated lands, by 0.18 mg·kg-1 of soil per year on the average on irrigated lands; exchangeable potassium - by 1.9 mg·kg-1 of soil per year on non-irrigated lands, by 3.1 mg·kg-1 of soil per year on the average on irrigated lands. The obtained result determines territorial priorities of the regional policies, making it possible to apply differential effectiveness of the soil-protecting block of agricultural systems. [ABSTRACT FROM AUTHOR]

Palaeogeographic markers can be justified among a large number of geochemical indicators in separate layers of pedosediments. This determines the need to develop a system of most information-rich pedogenetic indicators for reconstruction of the dynamics of erosion-accumulative processes based on dated earthen defensive constructions of the historical period. We demonstrated this solution at the example of a frontier rampart with a ditch of the mid-17th century ("Catena linking of landscape-geochemical processes and reconstruction of pedosedimentogenesis: a case study of defensive constructions of the mid-17th century, South Russia" [1]). Using individual of macroelements and trace elements as part of complex geochemical relationships and indicators allows us to determine the geochemical associations of elements that diagnose migration of the sediments at the trans -eluvial catenas. It is shown that in the forest-steppe conditions the determined system of pedogenic indicators, such as content of particles (%) with the size >0.01 and < 0.005 mm, pH H2O , CO 2, (CaО+MgO):Al 2 O 3, Si:Al, CaO:TiO 2, the eluviation coefficient, the association of mobile (Ca, Na, Mg, Sr) and weakly mobile (K, Ba, Rb) elements, the sum of the elements accumulated in the soil (P, Ca, K, Mg, Mn, Cu). They can be the basis of this classification and chronostratigraphy of pedosediments. The data obtained in these investigations are aimed at the establishment of soil-geomorphologic interrelations and calibration of mathematical models of natural processes., (© 2019 The Authors.)