The Probabilistic Nature of Humus and the Assessment of its Heterogeneity in Pedotransfer Models

A probabilistic assessment of spatial variability of humus content in soils in the river basin system and ravine catchment as its component in pedotransfer models of humus accumulation was carried out. The parameters of the relationship between natural and anthropogenic factors and the natural potential of ordinary Chernozem in steppe agrolandscapes on a basin basis were established. In order to reveal the peculiarities of the character of spatial distribution of humus content in soils of the Aidar River basin, confined to the upper, middle and lower reaches within the borders of the Lugansk People’s Republic (LPR), a statistical analysis of data from two rounds of a large-scale survey (1970 and 2011) was performed, the nature of long-term dynamics was revealed, statistical and probabilistic situations were analyzed, a schematic map of the modern spatial distribution of humus content was constructed, and a characteristic of the probability of its manifestation in various elements of the river basin → ravine catchment system was given. The principles of studying natural factors in pedotransfer models of soil formation include consistent mathematical and statistical analysis using GIS technologies and calculations by thematic stages: (1) determining the patterns of humus content and natural potential of ordinary Chernozem of steppe agrolandscapes from the parameters of granulometric composition, soil profile thickness, altitude above sea level and features of territory moisture through hydrothermal index of different periods of the year in the northern steppe; (2) forming pedotransfer models for determining the humus content and natural potential of humus reserves of ordinary Chernozem. Nonlinear pedotransfer models allow calculating the humus content of soils depending on the entire range of their values (minimum, average, maximum) and, taking into account the leading factors, constructing an optimization surface of the relationship between the humus content and natural factors.