Separation of periphery and inner parts of soil aggregates by mechanical abrasion

For separation of aggregates into the inner part (core) and periphery (cortex), abrasion of the aggregates against each other was used. For this purpose, aggregates of 5–3 mm were shaken on a reverse rotator, their core was ground off, passing to a fraction of <0.25 mm. To control the process, the abrasion efficiency was periodically assessed by changing the size fraction distribution. At the end of the experiment, the content of carbon and nitrogen was determined in the obtained fractions. The distribution of the obtained size fractions stabilized after 16 hours of the experiment, in the case of typical chernozem under the steppe, and after 24 hours in the case of sod-podzolic soil under the forest. In sod-podzolic soil, abrasion was observed throughout the experiment. In typical chernozem, after the first hour of processing, the crushing of aggregates prevailed, then in the next 10 h, abrasion prevailed, then crushing again. The determination of carbon and nitrogen shows the anisotropy of the aggregates by this parameter. Inside the aggregates, the carbon content is higher than on the periphery. Moreover, these differences are more pronounced in undisturbed soils, as well as in sod-podzolic soils compared to black soil. In general, the prospects of the proposed approach are shown. However, it requires further development for effective application.