Tracing soil erosion with Fe3O4 magnetic powder: Principle and application

Authors: SHI, HONGQIANG - Northwest A&f University; ZHAO, YAJUN - Northwest A&f University; AN, XIAOBING - Northwest A&f University; ZHENG, FENLI - Northwest A&f University; LIU, GANG - Northwest A&f University; LI, HAIRU - Northwest A&f University; Zhang, Xunchang; PAN, XUNCHENG - Northwest A&f University; WU, BINGLONG - Northwest A&f University; WANG, XUESONG - Northwest A&f University

Submitted to: International Soil and Water Conservation Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/7/2023
Publication Date: 8/10/2023
Citation: Shi, H., Zhao, Y., An, X., Zheng, F., Liu, G., Li, H., Zhang, X.J., Pan, X., Wu, B., Wang, X. 2023. Tracing soil erosion with Fe3O4 magnetic powder: Principle and application. International Soil and Water Conservation Research. 12:419-431. https://www.sciencedirect.com/science/article/pii/S2095633923000643.
DOI: https://doi.org/10.1016/j.iswcr.2023.08.002

Interpretive Summary: Magnetic powder is regarded as an effective and economical tracer for estimating soil erosion. However, the principle and application for using magnetic powder to estimate soil erosion are still not fully developed. In this study, magnetic powders with mean diameters of both 30 and 1 µm were mixed into three soils at different proportions to 1) establish the relationship between the magnetic susceptibility and the proportion of the introduced magnetic powder, 2) evaluate the binding ability of magnetic powder to soil particles after both dry and wet sieving, and 3) estimate errors of tracking soil loss. The results showed that there was a significant linear relationship between the magnetic susceptibility and the proportion of the introduced magnetic powder. The relationship between the amount of soil captured by a magnet and the proportion of magnetic powder in the tagged soil indicated that soils were readily magnetized by magnetic powder, especially for fine fractions. The magnetic susceptibility in different sizes of soil aggregates was variable. A majority of magnetic powder of both 30 and 1 µm diameters was strongly bound with fine particles <0.05 mm in dry and wet sieving. For three soils tested, the relative errors between the measured and estimated soil losses with correction of selective erosion using low-frequency measurement under the simulated rain events were less than 18.3%. This study proved the potentiality of using magnetic powder to trace soil erosion due to its low cost, ease of measurement and sufficient accuracy. The work provides another useful means to erosion scientists and soil conservationists for estimating soil erosion rates. USDAS is an equal opportunity employer and provider.

Technical Abstract: Magnetic powder is regarded as an effective and economical tracer for estimating soil erosion. However, the principle and application for using magnetic powder to estimate soil erosion are still not fully developed. In this study, magnetic powders with mean diameters of both 30 and 1 µm were mixed into three soils at different proportions. The relationship between magnetic susceptibility and the proportion of the introduced magnetic powder in the tagged soil, and the binding ability of magnetic powder to soil particles after both dry and wet sieving were investigated. The accuracy of tracking soil loss by using magnetic powder as a tracer was assessed. The results showed that there was a significant linear relationship between the magnetic susceptibility and the proportion of the introduced magnetic powder in the tagged soil. The relationship between the amount of soil captured by a magnet and the proportion of magnetic powder in the tagged soil indicated that soils were readily magnetized by magnetic powder, especially fine fractions. The magnetic susceptibility of magnetic powder in different sizes of soil aggregates was variable. A majority of magnetic powder of both 30 and 1 µm diameters was strongly bound with fine particles <0.05 mm in dry and wet sieving. For three soils tested, the relative errors between the measured and estimated soil losses with correction using low-frequency under the simulated rain events were less than 18.3%. This study proved the potentiality of using magnetic powder to trace soil erosion due to its low cost, easy measurement and sufficient accuracy. USDA is an equal opportunity employer and provider.