Form and orientation of soil pores as indicators of a structural soil organization

The work is based on the idea that the shape and orientation of soil pores are among the direct indicators of the structural state of the soil. The specific features of the quantitative assessment of the shape of pores in two-dimensional sections by the degree of its difference from the circle are considered. To improve the quality of the evaluation of the pore shape, it was proposed to use a generalized index of the pore shape F, which reflects both roundness and pore isometry. Using the form factor F, the structure of thin macropores was studied in vertical sections from the genetic horizons of the zonal loamy soils of the European territory of Russia. With the help of cluster analysis in the studied soils, 8 types of pore space specific for the main aggregative soil structures were identified. The selected types differ in shape, orientation and size of thin macropores in micromorphological sections. By means of discriminant analysis, a system of automated morphometric diagnostics of the aggregate soil structure based on the structure of the pore space of the soil has been developed. The natural genetic divergence of the aggregate structure in virgin soils and the agrogenic convergence of the structure in the arable horizons of agrosoils are shown. Morphometric criteria for diagnosing the four main stages of the degradation of the physical structure of the soil according to the shape and orientation of the soil pores are proposed.