Characterizing macropore structure of agrosoddy-podzolic soil using computed tomography

Aleksandra A Belik,Dmitry V Korost,Andrei G Bolotov,Aleksandr V Dembovetskii,Anna A Kokoreva,Alexei N Khomyak,Victoria N Kolupaeva

doi:10.1515/opag-2020-0080

Abstract

Abstract The agrosoddy-podzolic soil (Eutric Albic Glossic Retisol (Abruptic, Loamic, Aric, Cutanic)) is typical for Moscow Oblast and is used for agricultural purposes, resulting in use of various agrochemicals and pesticides. The presence of macropores and cracks in such soils leads to preferential water and substance transfer and nonequilibrium conditions. Therefore, it is important to study the numerical characteristics of the pore space of soils to adjust mathematical models of substance transfer. Undisturbed soil monoliths 10 cm in diameter taken from Ap (from 0 to 30 cm) and E, BE horizons (from 30 to 50 cm) were investigated under the field moisture conditions and after saturation using the tomographic core analyzer RKT-180 with the resolution of 200 μm/pixel. Using the X-ray computer tomography, it has been established that the plough layer of the agrosoddy-podzolic soil contains over 7% of macropores larger than 1 mm, while the subsurface layer has a porosity of about 3%. After saturation, some of the inter-aggregate pores overlap, which leads to a decrease in the total porosity to 4% in the upper and 2% in lower horizons, as well as increase in the average pore diameter. The number of macropores determined by tomographic analysis is one third higher than the values calculated using pedotransfer functions for this soil. The data obtained in this paper are recommended for use in national scenarios of migration of substances (pesticides, agrochemicals, salts) in soils.

Highlights

The pore space of soils has a complicated structure including water-conducting paths of various sizes and forms
Macropores and soil conduits can be caused by bioactivities, geological forces, or agrotechnical activities (Jarvis 2007)
The purpose of this paper is to study the macroporosity of agrosoddy-podzolic soil monoliths by tomographic method at saturated and unsaturated moisture for the adaptation of mathematic models of moisture and substance transport

Summary

Introduction

The pore space of soils has a complicated structure including water-conducting paths of various sizes and forms. Depending on their morphological characteristics, pores can be draining elements, store available soil water and nutrients, or contain unavailable water (Ivanov et al 2019). The bigger and more round a pore is, the less important sorption forces are and the faster filtration is; that is why, it is important to study large soil pores to control water quality and, for example, to manage pesticides. The front of a substance migration is not a uniform chromatic flow, and the movement of water and substances occurs through soil

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