The contribution of various organic matter fractions to soil–water interactions and structural stability of an agriculturally cultivated soil
The contribution of various organic matter fractions to soil–water interactions and structural stability of an agriculturally cultivated soil
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DOI：
10.1002/jpln.201700437
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发表时间：
2018-08
影响因子：
2.5
通讯作者：
C. Buchmann;G. Schaumann
中科院分区：
文献类型：
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作者：
C. Buchmann;G. Schaumann
土壤有机质和粘粒的存在及其相互作用是决定土壤结构稳定性的主要因素。在农业管理和环境可持续性的范围内，它仍然不清楚如何各种矿物质和有机质（OM）的馏分，OM-粘土相互作用和膨胀过程中的颗粒间的空间确定土壤-水的相互作用，从而土壤结构的稳定性。为了研究这一问题，我们通过土壤密度分级分离农业耕作粉质壤土的矿物和OM组分，并结合1H-NMR弛豫法、土壤流变学和土壤团聚体的单次湿筛分来评估它们的水化特征及其对土壤结构稳定性的影响。结果表明，农业管理措施，特别是堆肥和翻耕，以及各种有机质-粘土相互作用显着影响土壤-水相互作用和土壤结构稳定性。一方面，翻耕促进粘土膨胀，破坏土壤结构和减少有机质含量的结果，降低土壤结构的稳定性。另一方面，堆肥处理和减少耕作增加土壤结构稳定性。在所有情况下，土壤密度分级表明，堆肥衍生的颗粒有机物（POM）和矿物相关的有机物（MAOM）限制粘土膨胀，并导致高度多孔和机械稳定的土壤基质。特别是，POM增加土壤结构的稳定性，作为土壤团聚的核心，并通过限制粘土膨胀通过其存在的固体，颗粒间材料。与此相反，MAOM似乎通过粘土表面覆盖和粘性颗粒间水凝胶结构的形成来限制粘土溶胀。
The presence and mutual interactions of soil organic matter (SOM) and clay particles are major factors determining soil structural stability. In the scope of agricultural management and environmental sustainability, it remains unclear how various mineral and organic matter (OM) fractions, OM–clay interactions and swelling processes in the interparticle space determine soil–water interactions and thus soil structural stability. To investigate this issue, we isolated the mineral and OM fractions of an agriculturally cultivated silty loam soil by soil density fractionation and assessed their hydration characteristics and effects on soil structural stability combining ¹H‐NMR relaxometry, soil rheology and single wet‐sieving of soil aggregates. The results showed that agricultural management practices, in particular compost and ploughing, as well as various OM–clay interactions significantly affected soil–water interactions and soil structural stability. On the one hand, ploughing reduced soil structural stability by promoting clay swelling as a result of disrupted soil structures and reduced SOM content. On the other hand, compost treatment and reduced tillage increased soil structural stability. In all cases, soil density fractionation showed that compost‐derived particulate organic matter (POM) and mineral‐associated organic matter (MAOM) restricted clay swelling and resulted in a highly porous and mechanically stable soil matrix. In particular, POM increased soil structural stability by acting as nucleus for soil aggregation and by restricting clay swelling via its presence as solid, granular interparticulate material. In contrast, MAOM seemed to restrict clay swelling via clay surface covering and the formation of viscous interparticulate hydrogel structures.