Medium-term changes in the aggregate composition of southern chernozem under the influence of afforestation of the Penza-Kamensk state forest belt

For the first time, studies of the profile structure of the aggregate composition of chernozem have been carried out using dated samples from the Bioresource Collection of the Central Soil Museum by V. V. Dokuchaev. The degree and nature of the influence of 70-year-old forest plantations on the aggregate composition of arable soils have been established.

Introduction. In recent years, scientists have paid special attention to the study of the structure of aggregates, mechanisms and factors of formation of the percentage ratio of aggregates, i.e. fractions of different sizes, as well as aggregative stability and its influence on plant growth and productivity. Nevertheless, genetic aspects of aggregate percentage formation are less often studied. However, it should be noted that without studying the percentage ratio of aggregates as a typomorphic feature of soil-forming processes, it is difficult to predict changes in the percentage ratio of aggregates as a result of climate warming and anthropogenic impact. Thus, it is inevitably necessary to study the aggregate composition throughout the depth of the soil profile. The paper presents the results of the first research of the aggregate composition profile structure of southern chernozem using dated samples from the Bioresource Collection of the Central Museum of Soil Science. The degree and nature of the influence of 70-year-old forest plantations on the aggregate composition of arable soils were determined.

Object. The object of the study is textural carbonate chernozems (southern) at the station "Belye Prudy", located in Danilovsky district of Volgograd region.

Materials and methods. Soil samples were collected under two-year old tree plantings on arable land along a transect crossing three forest protection strips from west to east in 1950 and 2021 to a depth of 300 cm. A total of 3 soil transects were established with an average distance between transects of 360 m.

Results and conclusions. According to the results of the study, based on the comparative analysis of the percentage ratio of aggregates of soils, soil-forming and underlying rocks, the structure of the aggregate composition profile of southern chernozem on loess-like sediments was studied for the first time. It was found that the percentage of aggregates of southern chernozem was formed on a structured mineral matrix represented by loess-like clays. A comparative study of soil samples from 1950 and 2021 revealed a different degree and character of change in the aggregate composition of arable soils under the influence of afforestation. The structure coefficient corresponds to a good structural condition. No principal changes in the profile structure of the aggregate composition of arable soils during the period from forest planting to the mature state were revealed. Significant correlations were established in the content of aggregates of different sizes, as well as with the content of some fractions of granulometric composition. No correlations between the content of aggregate composition fractions, humus and environmental reaction (pH) were revealed.

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