The complex and accurate study of the soil structure in the arable chernozems agrogenic layer, within 12 pedogeographic areas between Prut and Dniester rivers has revealed a series of pedogeographic pattern:
- the agronomically valuable aggregates (10-0.25 mm) content in these soils usually are classified in the "very good" (˃ 80%) and "good" (60-80%) categories;
- the origin of the agronomically valuable aggregates from the arable layer is determined, mainly, by the mechanical and physical-mechanical processes and only partially by the root’s activity and physical-chemical mechanisms. Basically, the structural aggregates units due to the earthworm’s activity are absent. This implies the conclusion that in these chernozems arable layer the functional-processual changes take place so thorough, to soil biota can`t ensure anymore the high level of the organic matter humification processes and the biophilic elements stabilization in the soil (the last one determines the intensity of the soil aggregates forming by roots activity).
Therefore, we consider that in natural chain of the soil substance transformation, modeling-organization composition of the agrogenic layer the intensity of some processes, for which certain species of living organisms are responsible, is reduced. This get reflected to the soil aggregates hydrostability;
- soil aggregates with diameter ˃ 5 mm is characterized by low stability; 5-3 mm aggregates have poor hydrostability; 3-1 mm aggregates are characterized by moderate hydrostability; with maximal hydrostability are characterized the 1-0.25 mm aggregates;
- as the diameter of the soil aggregates is reduced, the soil aggregates density increases and their porosity is reduced, but when the soil aggregates diameter increases, the content of physical clay, fine silt, fine clay and humus content in their composition increases; there is a positive dependence between the soil aggregates diameters and their hydrostability.