Specificity of some soil characteristics in the rhizosphere of fir trees in the AEL horizon of podzolic soil

Abstract

The total number of bacteria, the length of the fungal mycelium, and some chemical properties are evaluated in the rhizosphere of fir (Picea abies) trees and out of the rhizosphere zone in the AEL horizon of podzolic soil in the Central Forest State Nature Biosphere Reserve (CFSNBR). In the rhizosphere soil, the total number of bacteria is found to be 1.5 times greater and the fungal mycelium length two times greater than in the soil outside of the rhizosphere. The rhizosphere soil is characterized by consistently higher content of Corg in the whole soil and in the clay and fine silt fractions due to the increase in microbial biomass and the continuous supply of organic substances from dead cells and root exudates. The rhizosphere soil has consistently lower values of pH in water and salt extracts and higher values of exchangeable acidity because of the more active functioning of soil biota and the input of protons with root exudates. The content of exchangeable potassium in the rhizosphere is higher than in the nonrhizosphere soil. This difference can be explained by the increase in potassium mobility in the illite–expandable minerals buffer system under more acid conditions and more active functioning of biota.