Explaining soil organic matter composition based on associations between OM and polyvalent cations
Explaining soil organic matter composition based on associations between OM and polyvalent cations
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DOI：
10.1002/jpln.201800093
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发表时间：
2018-10-01
影响因子：
2.5
通讯作者：
Gerke, Horst H.
中科院分区：
文献类型：
--
作者：
Ellerbrock, Ruth H.;Gerke, Horst H.
立地条件和土壤管理决定土壤有机质（SOM）的含量和组成。有机质 (OM) 的特点是具有优先与多价阳离子和土壤矿物质相互作用的官能团。这些相互作用或许可以利用基本土壤特性解释大量 SOM 和焦磷酸盐可溶性 OM 部分 (OM-PY) 的特定位点组成。本研究的目的是通过使用长期现场实验土壤数据来测试 OM 与多价阳离子（即 Ca、Mg、Al、Fe 和 Mn）之间相互作用的简化模型。该模型考虑了 (1) OM-阳离子、(2) OM-阳离子-矿物质和 (3) OM-矿物质关联，并假设阳离子与 OM 相互作用的配位位点的可用性取决于这三种类型的关联。该测试使用来自三个长期田间实验（哈雷、巴德劳赫施塔特、罗塔明斯特）的不同施肥地块的数据（表土）进行。 SOM 和 OM-PY 的组成通过 C=O（即此处表示羰基和羧基）的比率与从傅里叶变换红外 (FTIR) 光谱获得的 C-O-C 吸收带强度与可交换、草酸盐和连二亚硫酸盐可萃取多价阳离子的含量之间的关系来表征。当使用特定位点的可交换和草酸盐可提取的阳离子含量时，OM 和阳离子之间的假设关联以及配位位点的可用性解释了 SOM 的 C=O/C-O-C 比率的大部分变化，以及 OM-PY 的较少变化。对于来自定期施用农家肥的地块的样品，OM-PY 的 C=O/C-O-C 比率与地点无关。结果表明，一个简化模型可以用来改进对耕地土壤 OM 组成的位点特异性差异的解释，该模型根据关联类型考虑按每个阳离子的配位位点数量加权的多价阳离子含量。
Site conditions and soil management determine the content and the composition of soil organic matter (SOM). Organic matter (OM) is characterized by functional groups, which preferentially interact with polyvalent cations and soil minerals. These interactions could perhaps explain the site-specific composition of bulk SOM and a pyrophosphate-soluble OM fraction (OM-PY) using basic soil properties. The objective of this study was to test a simplified model for the interactions between OM and polyvalent cations (i.e., Ca, Mg, Al, Fe, and Mn) by using data from soils from long-term field experiments. The model considered (1) OM-cation, (2) OM-cation-mineral, and (3) OM-mineral associations and assumed that the availability of the cation's coordination sites for the interaction with OM depends on these three types of associations. The test was carried out using data (topsoil) from differently fertilized plots from three long-term field experiments (Halle, Bad Lauchstadt, Rotthalmunster). The composition of SOM and OM-PY was characterized by the relationship of the ratio of the C=O (i.e., here indicating both carbonylic and carboxylic groups) versus C-O-C absorption band intensities obtained from the Fourier transform infrared (FTIR) spectra with the content of exchangeable, oxalate-, and dithionite-extractable polyvalent cations. The assumed associations between the OM and cations and the availability of the coordination sites explained most of the variations in the C=O/C-O-C ratios of the SOM, and fewer variations in the OM-PY, when using the site-specific exchangeable and oxalate-extractable cation contents. The C=O/C-O-C ratios of the OM-PY were site-independent for samples from plots that regularly received farmyard manure. The results suggested that a simplified model that considers the polyvalent cation content weighted by the number of coordination sites per cation according to the type of association could be used to improve the explanation of site-specific differences in the OM composition of arable soils.