Changes in the Main Properties of Segregated Chernozems in Agroforest Landscapes of the Central Chernozem Region
The study of the evolutionary changes in the main properties of the chernozems of the Central Chernozem region in the conditions of agrocenoses and undisturbed ecosystems, depending on the influence of agrogenic and agroforestry factors, was carried out. The agrogenic influence was considered on the example of steppe (fallow) lands introduced into agricultural production. The forest-reclamation effect was understood as the effect of a protective forest strip on the soil cover. It is shown that the chernozems of the Stone Steppe are characterized by a significant spatial variation of the main indicators of soil fertility. An increase in the duration of anthropogenic use of chernozems led to a significant decrease in the humus potential of soils with a simultaneous decrease in spatial variation due to the homogenization of the arable horizon. The coefficient of variation of the humus content in the 0–10 cm layer of soil decreased on arable land compared to the fallow and forest strip, respectively, from 7.21 and 8.12 to 3.63%. The content of humus on arable land in a layer of 0–10 cm of soil decreased from 11.0 to 7.42% compared to the deposit. Agrogenic and forest-reclamation effects were accompanied by a change in the composition of the humus of the studied chernozem soils. In the upper layers of the soil (0–10 and 10–20 cm), the ratio of  C<sub>GA</sub> : C<sub>FA</sub> increased on arable land and in the forest strip to 4.78–6.71 compared to the deposit, in the lower layers (20–40 cm), on the contrary, there was a decrease in this ratio. There was also a decrease in the content of non-hydrolyzable residue (in % of total carbon) in arable soils compared to the deposit on average from 30 to 10%. The degree of humification in the forest strip and on arable land increased from 56 to 58 and 75%, respectively, compared to the deposit. When the deposit was introduced into agricultural and forest reclamation use, the redistribution of the composition of the exchange bases of the soil was noted not only in space, but also with depth. In the upper layers (0–10 cm), the maximum content of exchangeable calcium was found in the soils of the forest strip, the minimum – on arable land. With a depth of (20–40 cm), the minimum magnesium content is noted in the deposit. Long-term agrogenic and forest-reclamation effects on chernozem soils were accompanied by certain changes in soil acidity. In all the studied objects, except for arable land, the reaction of the soil environment for several decades shifted to the alkaline side by 0.07–0.55 pH units. Some statistical characteristics of the distribution of the main physical and chemical indicators and indicators of the humus state of chernozems were calculated. On their basis, isoplets of a two-dimensional distribution of indicators of the main properties of chernozem soils of the studied experimental site were constructed.