Using micromorphological techniques for geometrical classification of soil aggregates affected by various treatments

The wetting drying cycles, through the creation of Swelling Shrinkage sequences in soil aggregates, lead to changes in the soil's microstructure. In this study, attempts were made to investigate changes in the geometric properties of loamy sand and silty clay soils by applying moisture cycles in different treatment conditions, including amendmentsand degradations. The hypothesis of this research is based on the premise that the presence of different treatment intensities of the effects of wetting drying cycles affects the soil's microstructure from the perspective of soil aggregates. Using ImageJ software, image processing was performed on 2D and 3D images acquired from soil blocks. In addition to soil aggregate volume and surface area, properties such as sphericity and flatness coefficients were estimated and used for the classification of soil aggregates. For statistical analysis and chart plotting, Orange 3 and Excel 2016 software were used. The results indicated that treatments such as calcium carbonate, cations, and organic matter increased the coefficient of soil aggregates elongation, while degradation treatments led to an increase in the coefficient of soil aggregates flatness in both studied soil textures. Geometric classification of soil aggregates revealed that a small portion of loamy sand soil aggregates were categorized as elongated soil aggregates, while more than half of them fell into the category of flatted soil aggregates. In silty clay soil samples, a uniform distribution of elongated, bladed, and flatted soil aggregates was observed. However, none of the studied treatments resulted in soil aggregates falling into the category of compacted soil. Considering the direct impact of soil aggregate shape on the hydraulic conductivity of soils, the method employed in this research can effectively determine the microstructural status of soils from the perspective of soil aggregates.