Formation of soil organic matter via biochemical and physical pathways of litter mass loss
Formation of soil organic matter via biochemical and physical pathways of litter mass loss
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DOI：
10.1038/ngeo2520
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发表时间：
2015-10-01
影响因子：
18.3
通讯作者：
Parton, Andwilliam J.
中科院分区：
文献类型：
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作者：
Cotrufo, M. Francesca;Soong, Jennifer L.;Parton, Andwilliam J.
土壤有机质是最大的陆地碳库（1）。土壤有机碳库的大小取决于植物凋落物分解形成的土壤有机质与其矿化为无机碳之间的平衡。土壤有机质形成的知识仍然有限（2），目前的C数值模型假设稳定的土壤有机质主要由柠檬植物凋落物形成（3）。然而，植物凋落物的不稳定成分也可以形成矿物稳定的土壤有机质（4）。在这里，我们遵循的同位素标记的地上凋落物的分解和纳入土壤有机质超过三年在美国堪萨斯的草原，并使用实验室培养，以确定衰减率和池结构的凋落物衍生的有机质。在分解的早期，当非结构性化合物从凋落物中丢失时，形成了土壤有机质。土壤有机质也形成在分解结束时，当非结构和结构化合物以相似的速率丢失。我们得出结论，两种途径有效地产生土壤有机质。当枯枝落叶失去大部分非结构化合物时，溶解有机物-微生物路径在分解早期发生，这些化合物以高速率掺入微生物生物量，从而有效地形成土壤有机物。一个同样有效的物理转移路径发生时，凋落物碎片进入土壤。
Soil organic matter is the largest terrestrial carbon pool(1). The pool size depends on the balance between formation of soil organic matter from decomposition of plant litter and its mineralization to inorganic carbon. Knowledge of soil organic matter formation remains limited(2) and current C numerical models assume that stable soil organic matter is formed primarily from recalcitrant plant litter(3). However, labile components of plant litter could also form mineral-stabilized soil organic matter(4). Here we followed the decomposition of isotopically labelled above-ground litter and its incorporation into soil organic matter over three years in a grassland in Kansas, USA, and used laboratory incubations to determine the decay rates and pool structure of litter-derived organic matter. Early in decomposition, soil organic matter formed when non-structural compounds were lost from litter. Soil organic matter also formed at the end of decomposition, when both non-structural and structural compounds were lost at similar rates. We conclude that two pathways yield soil organic matter efficiently. A dissolved organic matter-microbial path occurs early in decomposition when litter loses mostly non-structural compounds, which are incorporated into microbial biomass at high rates, resulting in efficient soil organic matter formation. An equally efficient physical-transfer path occurs when litter fragments move into soil.