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Linkages between soil organic matter and magnetic mineral formation in agricultural fields in southeastern Minnesota, USA
Geoderma ( IF 6.1 ) Pub Date : 2021-09-27 , DOI: 10.1016/j.geoderma.2021.115466
Aaron L. Frankl 1, 2 , Daniel P. Maxbauer 1 , Mary E. Savina 1
Affiliation  

Magnetic properties of soil are widely utilized to study soil development in a variety of settings due to the formation of strongly magnetic iron oxides during pedogenesis. Similarly, soil organic matter (SOM) is commonly measured in soil surveys conducted on agricultural lands due to the essential role SOM plays in the soil ecosystem. Here, we present data from two agricultural fields in southeastern Minnesota that demonstrate a relationship between soil magnetic properties and SOM. In each field, we collected 100 topsoil samples along a 40 m by 20 m grid to determine spatial variability in soil magnetic properties and SOM, as well as two soil cores to constrain variability with depth (∼0–60 cm). Magnetic susceptibility, low-field remanence, and hysteresis properties were used to characterize magnetic mineral abundance and grain-size in the soils. There are strong positive correlations between SOM and three magnetic properties: the frequency dependence of susceptibility (χfd), anhysteretic remanent magnetization (ARM), and the ratio of ARM to isothermal remanent magnetization (ARM/IRM). All three of these magnetic properties (χfd, ARM, and ARM/IRM) are sensitive to the concentration (or relative abundance) of fine-grained (<75 nm) magnetite/maghemite known to form in well-drained soils during pedogenesis. Correlation between SOM and magnetic properties persist in each field despite differences in the management strategy over the past three decades. Our results support a functional link between SOM and soil-formed magnetite/maghemite, where increasing SOM (up to a threshold) enhances the production and stability of soil-formed magnetite due to its role in soil redox processes and iron-organic complexes. Agricultural soils seem particularly well suited to demonstrate correlations between SOM and pedogenic magnetic minerals due to their relatively low SOM and typically well-drained environments, supporting the utility of soil magnetism in agricultural soil survey studies.



中文翻译:

美国明尼苏达州东南部农田土壤有机质与磁性矿物形成的关系

由于在成土过程中形成强磁性氧化铁,土壤的磁性被广泛用于研究各种环境中的土壤发育。同样,由于 SOM 在土壤生态系统中的重要作用,土壤有机质 (SOM) 通常在农田土壤调查中进行测量。在这里,我们展示了来自明尼苏达州东南部两个农田的数据,这些数据证明了土壤磁性和 SOM 之间的关系。在每个领域,我们沿 40 m x 20 m 网格收集了 100 个表土样品,以确定土壤磁特性和 SOM 的空间变异性,以及两个土壤核心,以限制随深度(~0-60 cm)的变异性。磁化率、低场剩磁和磁滞特性用于表征土壤中的磁性矿物丰度和粒度。fd )、非滞回剩磁 (ARM) 以及 ARM 与等温剩磁的比值 (ARM/IRM)。所有这三个磁特性 (χ fd,ARM 和 ARM/IRM) 对已知在成土过程中排水良好的土壤中形成的细粒 (<75 nm) 磁铁矿/磁赤铁矿的浓度(或相对丰度)敏感。尽管过去 30 年的管理策略存在差异,但 SOM 和磁性之间的相关性在每个领域都存在。我们的结果支持 SOM 与土壤形成的磁铁矿/磁赤铁矿之间的功能联系,其中增加 SOM(达到阈值)可提高土壤形成的磁铁矿的产量和稳定性,因为它在土壤氧化还原过程和铁有机复合物中的作用。农业土壤似乎特别适合证明 SOM 与成土磁性矿物之间的相关性,因为它们的 SOM 相对较低且通常排水良好的环境,支持土壤磁性在农业土壤调查研究中的效用。

更新日期:2021-09-27
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