Physical-Tomographic Characteristics and Structure of Bacterial Community of the Agrophysical System “Germinating Roots—Pore Space of Soils” (Physical Model Experiment)

Computed tomography allows quantifying the volume of elements of soil solids, pore space, and root system. It was possible to record the dynamics of changes in the soil pore volume space within the framework of a special physical model experiment with cultivation of barley seedlings for 7 days and tomographic imaging at key stages. The main goal was to quantify the structural changes in the development of root system and their dynamics. The experiment has been carried out in the samples of soddy-podzolic soil and chernozems; along with changes in the soil structure, changes in the structure of the microbial community have been recorded in the agrophysical system “germinating roots–pore space.” Models of the seedbed were created in plastic buckets with a volume of 3 cm3 with two layers: the subseminal layer compacted to 1.2 g/cm3 and the above-seed aggregated layer with a density of 0.7–0.8 g/cm3. Seeds of barley (Hordeum vulgare L.) of the Mikhailovskii variety were placed on the boundary of these layers. Soil water content was maintained close to the field capacity. As germination progressed from 3 to 7 days, a tomographic survey and a study of the microbiological community were carried out by gas chromatography-mass spectrometry. During this period, a decrease in the tomographic porosity in the subseminal layer and a change in the number of microorganisms, that mainly perform the destruction of complex carbon compounds, were recorded. Tomographic and microbiological studies have shown the interconnections between the processes occurring during seed germination and can be used to quantify the emerging root system.