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Visualizing the transfer of organic matter from decaying plant residues to soil mineral surfaces controlled by microorganisms
Soil Biology and Biochemistry ( IF 9.7 ) Pub Date : 2021-06-22 , DOI: 10.1016/j.soilbio.2021.108347
Alix Vidal , Tobias Klöffel , Julien Guigue , Gerrit Angst , Markus Steffens , Carmen Hoeschen , Carsten W. Mueller

The interface between decaying plant residues and soil minerals represents an essential soil microenvironment at which soil organic matter forms. The high amount of microbial products and residues within this hot spot of microbial activity fosters the formation of mineral-associated organic matter. Besides classical quantitative analyses, our understanding of processes controlling soil organic matter formation greatly benefits from microscopic observations and measurements, which provide spatially resolved information at a meaningful scale for microbial processes and for the association between organic and mineral particles. We studied carbon and nitrogen transfer from fresh-plant residues to the mineral soil, through a litter decomposition experiment in an artificial soil mixture. Needles of Norway spruce (Picea abies L.) were placed in microbatch containers filled with an artificial soil mixture free of soil organic matter. Containers were buried in fresh organic layer material from a Norway spruce stand and incubated for 14 and 42 days. We applied nanoscale secondary ion mass spectroscopy (NanoSIMS) to investigate the spatial distribution of mineral and organic compounds at the needle vicinity and into the mineral soil (0–550 μm from the needle). After 14 days, we depicted the formation of mineral-associated organic matter in the surrounding of the decaying needles. After 42 days, we observed substantial colonization of the needles and the detritusphere by saprotrophic fungi. The fungal hyphae extended into the mineral matrix of the artificial soil acting as vectors for the transfer of litter-derived carbon and nitrogen into the bulk soil. This resulted in an increase of the area covered by organic matter in the detritusphere, with up to 10% of the total investigated area classified as organic matter closely associated with mineral surfaces. Our results provide evidence that the carbon and nitrogen derived from litter decomposition transformed by microorganisms is transferred as mineral-associated organic matter, heterogeneously distributed from the litter source, and still detected 550 μm away from the latter. The close association of newly formed soil organic matter and fine sized minerals suggests that the formation of mineral-associated OM and likely also microaggregates is directly driven by microbial activity in the vicinity of hot spots for plant carbon input (e.g. the detritusphere).



中文翻译:

可视化有机物质从腐烂的植物残留物转移到由微生物控制的土壤矿物表面

腐烂的植物残体和土壤矿物质之间的界面代表了土壤有机质形成的基本土壤微环境。这个微生物活动热点内的大量微生物产物和残留物促进了矿物相关有机物的形成。除了经典的定量分析外,我们对控制土壤有机质形成过程的理解极大地受益于微观观察和测量,微观观察和测量为微生物过程以及有机和矿物颗粒之间的关联提供了有意义的空间分辨率信息。我们通过人工土壤混合物中的凋落物分解实验研究了碳和氮从新鲜植物残留物到矿质土壤的转移。挪威云杉针叶 ( Picea abiesL.) 放入装有不含土壤有机质的人造土壤混合物的微批次容器中。将容器埋在来自挪威云杉林的新鲜有机层材料中并孵育 14 天和 42 天。我们应用纳米级二次离子质谱 (NanoSIMS) 来研究针附近和矿质土壤中矿物和有机化合物的空间分布(距针 0-550 μm)。14 天后,我们描绘了在腐烂的针叶周围形成与矿物质相关的有机物质。42 天后,我们观察到腐生真菌对针叶和碎屑层的大量定植。真菌菌丝延伸到人造土壤的矿物基质中,作为将凋落物衍生的碳和氮转移到大块土壤中的载体。这导致碎屑层中有机质覆盖的面积增加,高达 10% 的总调查面积被归类为与矿物表面密切相关的有机质。我们的结果提供证据表明,微生物转化的凋落物分解产生的碳和氮作为矿物相关有机物转移,从凋落物来源异质分布,并且仍然在距后者 550 μm 处检测到。新形成的土壤有机质与细粒矿物质的密切关联表明,与矿物质相关的 OM 以及微团聚体的形成直接由植物碳输入热点(例如碎屑层)附近的微生物活动驱动。多达 10% 的总调查区域被归类为与矿物表面密切相关的有机物质。我们的结果提供证据表明,微生物转化的凋落物分解产生的碳和氮作为矿物相关有机物转移,从凋落物来源异质分布,并且仍然在距后者 550 μm 处检测到。新形成的土壤有机质与细粒矿物质的密切关联表明,与矿物质相关的 OM 以及微团聚体的形成直接由植物碳输入热点(例如碎屑层)附近的微生物活动驱动。多达 10% 的总调查区域被归类为与矿物表面密切相关的有机物质。我们的结果提供证据表明,微生物转化的凋落物分解产生的碳和氮作为矿物相关有机物转移,从凋落物来源异质分布,并且仍然在距后者 550 μm 处检测到。新形成的土壤有机质与细粒矿物质的密切关联表明,与矿物质相关的 OM 以及微团聚体的形成直接由植物碳输入热点(例如碎屑层)附近的微生物活动驱动。我们的结果提供证据表明,微生物转化的凋落物分解产生的碳和氮作为矿物相关有机物转移,从凋落物来源异质分布,并且仍然在距后者 550 μm 处检测到。新形成的土壤有机质与细粒矿物质的密切关联表明,与矿物质相关的 OM 以及微团聚体的形成直接由植物碳输入热点(例如碎屑层)附近的微生物活动驱动。我们的结果提供证据表明,微生物转化的凋落物分解产生的碳和氮作为矿物相关有机物转移,从凋落物来源异质分布,并且仍然在距后者 550 μm 处检测到。新形成的土壤有机质与细粒矿物质的密切关联表明,与矿物质相关的 OM 以及微团聚体的形成直接由植物碳输入热点(例如碎屑层)附近的微生物活动驱动。

更新日期:2021-07-05
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