Non-Destructive Measurement of Soil Porosity and Attenuation Coefficient Using Gamma-Ray Technique in Jalgaon Region of Maharashtra

Abstract

Soil porosity is an important parameter governing water holding, drying, and soil structure. In this work, a non-destructive gamma-ray attenuation technique was used to determine soil bulk density, porosity, and attenuation coefficients for soil samples collected from the Jalgaon district, Maharashtra, India. Gamma-ray measurements were carried out using sealed ¹³?Cs (661.657 keV) and ??Co (1173.228 keV and 1332.492 keV) sources with a NaI(Tl) scintillation detector. Bulk density values ranged from 0.85 to 1.09 g cm?³, while porosity varied between range of 45.5% and 57.5%. The result shows that the inverse relationship between bulk density and porosity was observed. Linear attenuation coefficients increased with soil density but decreased with increasing photon energy, whereas mass attenuation coefficients showed smaller variations. The results confirm that gamma-ray attenuation is a reliable and effective method for non-destructive soil characterization.

Introduction

Soil porosity (?) represents the fraction of pore spaces within soil, typically ranging from 30–60%, which influences water retention, aeration, permeability, and soil health. Pore structure affects root growth, microbial activity, nutrient transport, and gas exchange. Coarse soils have larger but fewer pores, while fine soils have smaller, more numerous pores.

Traditional methods to measure porosity—like bulk density and gravimetric approaches—are time-consuming and may disturb soil structure. Non-destructive gamma-ray techniques such as gamma-ray spectroscopy (GRS) and computed tomography (CT) allow rapid and accurate soil characterization. Using GRS, soil bulk density (ρ?), mass attenuation coefficient (μ?), and porosity can be estimated via gamma-ray attenuation based on the Beer–Lambert law.

In this study, agricultural soil samples from North Maharashtra, Jalgaon were analyzed using ??Co and ¹³?Cs gamma sources. Soil samples were placed in cylindrical containers, and gamma-ray transmission through the samples was measured using a NaI(Tl) scintillation detector. Linear (μ) and mass attenuation coefficients (μ?) were calculated, showing that μ increases with soil bulk density and decreases with gamma-ray energy. Mass attenuation coefficients depend more on chemical composition than density. This approach enables non-destructive estimation of soil porosity, offering a reliable tool for soil physical and environmental studies.

Conclusion

In this work, the gamma-ray attenuation technique was successfully applied to estimate soil porosity and attenuation coefficients in soil samples. The method proved to be non-destructive, reliable, and sensitive to variations in soil density and structure. Among the analyzed samples, the Yawal region soil exhibited the highest porosity (57.48%), while the Jamner region soil showed the lowest porosity (45.54%). The results confirm that soil porosity plays a significant role in determining the water-retention capability of soil. The linear attenuation coefficient (?) was found to increase with increasing bulk density, as denser soils provide a greater number of atoms per unit volume for interaction. In contrast, the mass attenuation coefficient (??) showed comparatively smaller variation among the samples, indicating its stronger dependence on soil composition rather than bulk density alone. Overall, the results demonstrate that gamma-ray attenuation measurements can effectively be used for simultaneous estimation of bulk density, porosity, and attenuation properties of soils. The gamma-ray techniques can be efficiently employed for soil characterization, offering valuable applications in environmental monitoring, agriculture, and nuclear data studies.

References

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Copyright

Copyright © 2026 V. G. Ahire, R. L. Shilkande, V. D. Bharud. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.