Structural state of chernozem after long-term post-agrogenic transformation

The purpose. To determine the main laws of transformation and regulatory parameters of the structural state change of chernozems of the forest-steppe zone in conditions of long-term post-agrogenic transformation according to the results of dry sieving of soil samples and statistical analysis of the data using the method of principal components, factor and non-parametric analysis. Methods. Laboratory analytical, experimental field, statistical. Results. The performed statistical processing of results of the analysis of dry sieving of the structure of chernozems in the long-term post-agrogenic state demonstrates the promise of using factor, cluster and non-parametric analysis methods. An important role in the restoration of the structure of chernozems is played by a combination of structural units 3.0–0.5 mm in size, with which the additional density in the humus horizon is inversely proportional, and with the humus content, it is directly proportional. The carried out clustering indicates that the content of the presented chernozems in the state of virgin soil and long-term deposits is the separated and not similar state of soil objects. But there is a general pattern of formation of a set of structural units of 3.0-0.5 mm similar to chernozems in the state of virgin soil, which content exceeds 40-50% of the content of parts in the agronomically valuable interval. Conclusions. After withdrawal from agricultural circulation, chernozems of agrocenoses enter into a complex process of self-healing, which goes in the direction of the virgin zone type. During post-agrogenic evolution, the accumulation of total humus occurs and the structural organization of the arable layer is gradually restored. In the first 20-25 years, there is a noticeable increase in the share of macroaggregates, including agronomically valuable ones, and the corresponding decrease in the number of microaggregates, which indicates an improvement in agronomic properties of shifted chernozems. In accordance with the number of agronomically valuable aggregates, all chernozems of the represented fallow series are characterized as excellent, and the dynamics of the growth of the structural coefficient increases with age towards virgin soil.