Work

Changes in Soil Magnetic Susceptibility and the Environmental Implications under the Conversion of Soda Saline–Alkaline Wastelands into Paddy Fields

Year: 2025

Type: article

Abstract: ABSTRACT The magnetic susceptibility (MS, including low‐frequency mass‐specific magnetic susceptibility χlf and percent of frequency‐dependent magnetic susceptibility χfd%) of soil is crucial for indicating pedogenic processes and indirectly affects soil fertility. Alternating drought and waterlogging significantly decreased the MS (χlf and χfd%) of soil. In the western Songnen Plain of China, converting soda saline–alkaline wastelands into paddy fields causes continuous drought–waterlogging alternation of the soil. In this study, we aimed to reveal the environmental implications of MS (χlf and χfd%) throughout this conversion and develop an identification method for soda saline–alkaline soils based on the relationship between the MS (χlf and χfd%) and saline–alkaline indicators. Topsoil samples (0–20 cm) were collected from a soda saline–alkaline paddy field and wasteland in Niuxintaobao County, Da'an City, Jilin Province, China. Based on the MS (χlf and χfd%) and saline–alkaline indicators (e.g., total dissolved solids TDS, exchangeable sodium saturation percentage ESP, cation exchange capacity CEC, exchangeable sodium ENa) of soil, correlation analysis and structural equation modeling using maximum likelihood estimation (ML‐SEM) were conducted. The results revealed that the χlf and χfd% of paddy soil were lower than those of soda saline–alkaline wasteland. It's due to long‐term waterlogging and human disturbances like irrigation, fertilization, and cultivation. Soda saline–alkaline soils are inherently less magnetic than other soil types. Under waterlogged and reducing conditions, ferrous magnetic minerals are destroyed, causing further magnetic attenuation during Hydragric Anthrosols' evolution. Generally, the MS (χlf and χfd%) of black soils ranges from 10 < χlf < 100 (× 10−8 m3 kg−1) and 2% < χfd% < 10%. In contrast, research shows that χlf < 14 ×10−8 m3 kg−1 (Mean ± SD = 9.26 ± 1.56) and χfd% < 4% (Mean ± SD = 2.46 ± 1.05) are suggested to be diagnostic characteristics of the surface layer of soda saline–alkaline soils in Northeast China. The correlation analysis and ML‐SEM results indicate that the main factors influencing χlf in the paddy soils were the ENa, Cl−, TDS, ESP, Na+, and SO42−, with net effects of −0.990, 0.688, −0.3502, −0.3000, 0.2331, and 0.1746. ENa, TDS, and ESP significantly inhibited the χlf of paddy soils, while the Cl−, Na,+ and SO42− contents significantly promoted it. In contrast, the χfd% of the soils showed no correlation with any of these indicators. The χlf of paddy soils variations can indirectly indicate the fluctuations of soil saline–alkaline indicators. In sum, MS (χlf and χfd%) can serve as an alternative index for describing changes in soil salinization levels and has potential implications for soil salinization assessment.

Source: Land Degradation and Development

DOI: 10.1002/ldr.5572

Authors: Xintong Liu, Liang Liu, Ruijiao Hou, Mingji Jin, Hongyuan Liu

Institutions: Yanbian University, Chinese Academy of Sciences, Northeast Institute of Geography and Agroecology, Nanjing Forestry University

Language: English

Topic: Geomagnetism and Paleomagnetism Studies

Subfield: Molecular Biology

Field: Biochemistry, Genetics and Molecular Biology

Domain: Life Sciences

SDGs: Life on land, Clean water and sanitation, Zero hunger

Open Access status: bronze

Funders: Chinese Academy of Sciences, People's Government of Jilin Province, National Key Research and Development Program of China