Influence of Robinia pseudoacacia L. and Quercus robur L. artificial forest plantations on the particle-size distribution of calcic chernozem

The particle-size distribution is one of the most important characteristics of soils, which determines most of their properties and features of the main regimes. Artificial forest plantations in the steppe act as a powerful environment-transforming factor, which over time is capable of changing even quite conservative properties of soils, including their particle-size distribution. The study of the influence of forest plantations on the particle-size distribution was carried out using soil samples taken from calcic chernozem, chernozem under the plantation of R. pseudoacacia L. and under the plantation of Q. robur L. The determination of the particle-size distribution was carried out by the pipette method, with the preparation of the sample by trituration with a solution of sodium pyrophosphate. The classification of granulometric fractions is given according to N. A. Kaczynskii. The analysis of the characteristics of the ratio of particle-size distribution of the studied chernozems revealed that the zonal chernozem is characterized by an increased content of the sand fraction and a reduced content of the silt fraction in the H1 and H2 horizons compared to the lower horizons. The calcic chernozem under the plantation of R. pseudoacacia L. is characterized by a relatively uniform distribution of the content of sand, dust and silt fractions along the soil profile. In calcic chernozem under the plantation of Q. robur L., the maximum content of the sand fraction was found in the surface horizon, with a gradual decrease in the content of this fraction with depth, while the content of dust and silt fractions increased with depth. The growth of R. pseudoacacia L. and Q. robur L. plantations on calcic chernozems leads to an increase in the content of sand fractions and a decrease in dust and physical clay fractions. There is also a certain change in the profile distribution of fractions, especially sand, under the influence of the growth of forest plantations. Each of the investigated calcic chernozems is characterized by a specific ratio of «sand : dust : silt» fractions, which indicates a different genesis of granulometric fractions.