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

Document Type : Research Paper

Authors

• aida Bakhshi khorramdarre ¹
• Parisa Alamdari ²
• Ahmad Heidari ³
• Mohammad Hosein Mohammadi ⁴
• Ehsan Ghezelbash ⁴

¹ Department of Soil science, faculty of agriculture, university of Zanjan, Zanjan, Iran.

² Soil science department, faculty of agriculture, university of Zanjan, Zanjan, Iran.

³ Department of Soil Science and Engineering, Faculty of Agricultural Engineering and Technology, University of Tehran, Karaj, Iran

⁴ Department of Soil Science and Engineering, Faculty of Agricultural Engineering and Technology, University of Tehran, Karaj, Iran.

Abstract

Keywords

• Image analysis
• Soil aggregates elongation
• soil aggregates flatness
• Soil microstructure
• Wetting-drying cycles

Main Subjects

• پیدایش و رده‌بندی خاک

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

EXTENDED ABSTRACT

Background:

 Soil microstructure plays a pivotal role in its overall health and functionality. Wetting‌drying cycles, which induce Swelling‌Shrinkage sequences in soil aggregates, are known to have a significant impact on soil microstructure. This study sought to explore the alterations in the geometric properties of two distinct soil types, namely loamy sand and silty clay, by subjecting them to varying moisture conditions, involving both enhancements and deteriorations. The central premise of this research revolves around the notion that different levels of treatment intensity during wetting‌drying cycles exert discernible effects on soil microstructure at the soil aggregate level.

Objective

The primary objective of this research was to investigate how wetting‌drying cycles, with differing treatment conditions, influence the microstructural attributes of loamy sand and silty clay soils. These treatment conditions encompassed the application of amendments like calcium carbonate, cations, and organic matter, as well as degradation processes. The aim was to discern how these treatments impact soil aggregate shape, volume, surface area, sphericity, and flatness coefficients, with the ultimate goal of classifying the soil aggregates based on their geometric attributes.

Methodology

To achieve this objective, the study employed advanced techniques. Soil blocks were subjected to wetting‌drying cycles, and 2D and 3D images of the soil aggregates were captured. Image processing was carried out using ImageJ software to extract valuable information. The parameters of interest included soil aggregate volume, surface area, sphericity, and flatness coefficients. These parameters served as the basis for the classification of soil aggregates. Statistical analysis and visualization were conducted using Orange 3 and Excel 2016 software to draw meaningful insights from the data.

Findings

 The study's findings shed light on the significant impacts of the different treatments on soil microstructure. Treatments involving the addition of calcium carbonate, cations, and organic matter resulted in an increase in the coefficient of soil aggregate elongation. Conversely, degradation treatments led to an increase in the coefficient of soil aggregate flatness in both the loamy sand and silty clay soils. Further analysis revealed that in loamy sand soil samples, a small portion of the soil aggregates could be categorized as elongated, whereas more than half fell into the category of flattened soil aggregates. In silty clay soil samples, a more uniform distribution of elongated, bladed, and flattened soil aggregates was observed. However, none of the treatments led to soil aggregates being categorized as compacted soil.

Conclusion

This study underscores the critical significance of soil aggregate shape in shaping soil hydraulic conductivity and, by extension, its impact on agriculture, environmental science, and geotechnical engineering. The research methodology demonstrated its effectiveness in providing a comprehensive view of soil microstructure dynamics under the influence of wetting‌drying cycles and diverse treatment conditions. These insights are invaluable, contributing to a more profound comprehension of how soils react to environmental changes. Such knowledge is vital for sustainable land management and agriculture practices, facilitating optimized irrigation, resource conservation, and enhanced crop yields. Beyond agriculture, it holds substantial ecological implications by enabling us to better mitigate the effects of climate change and soil degradation. Moreover, in geotechnical engineering, it offers a powerful tool to improve the safety and durability of civil engineering projects. Overall, this study's findings serve as a foundation for more informed and sustainable practices in a world where responsible land use and environmental stewardship are increasingly critical.