Modern technologies make it possible to obtain a lot of diverse information about the soil properties using satellite images, but field studies are also required to create or refine digital soil maps. To create a digital soil map scaled 1:25 000 in 2016, a classical field study was conducted with the laying of soil sections in places with the same coordinates as in the mapping of 1982. It allowed to carry out retrospective monitoring of transformation of morphogenetic and agrochemical properties of soils of the southern forest-steppe of the Republic of Bashkortostan (Russia) for the 34-year period of farm use. Thus, the correction and digitization of the soil map allowed to establish that arable land occupies 69.792 ha (67.9%) in the structure of agricultural land (102 811 ha). The monitoring showed deterioration of the main characteristics of arable soil fertility: the diminishing of humus-accumulative horizons, significant decrease of humus content (p ≤ 0.05), a small but reliable acidification of the medium reaction and reducing labile phosphorus. Losses of organic matter occurred mainly in the most fertile soils; their proportion decreased from 55.9% of the total area of agricultural land to 12.4%.

The article provides an assessment of soil fertility indicators of agricultural lands in the northern foreststeppe of the Republic of Bashkortostan within the Iglinsky region (Russian Federation). The content of humus, mobile phosphorus, exchangeable potassium, the thickness of the humus horizon, granulometric composition, morphological properties and soil washout were studied. It was revealed that the soil-forming process occurs on rocks of different ages and genesis, such as diluvial carbonate and carbonate-free clays and heavy loams, limestone eluvium, sandstone eluvium and alluvial deposits, which determine the diversity of the soil cover. In the study area, water erosion processes are developing, influenced by anthropogenic and natural factors such as planar and linear washout on slopes with a steepness of more than 2–3° and high ploughing of agricultural land. In terms of humus content, low-humus and medium-humus soils are widespread, accounting for 45.5 and 40%, respectively. The soil map was corrected and digitised to identify the main types and subtypes of soils, indicating the varieties at a scale of 1: 25,000. Digitised maps, taking into account the current state of soil fertility, are used to develop projects for inter-farm and intra-farm land management of organisations of the agro-industrial complex, state cadastral valuation of agricultural land, determination of land tax and development of measures to improve soil fertility.