Carbon and nitrogen storage and stability by mineral-organic association in physical fractions of anthropogenic dark earth and of reference soils in Amazonia
Carbon and nitrogen storage and stability by mineral-organic association in physical fractions of anthropogenic dark earth and of reference soils in Amazonia
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DOI：
10.1016/j.catena.2022.106185
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发表时间：
2022-06
期刊：
影响因子：
6.2
通讯作者：
Bruna Ramalho;J. Dieckow;Vander de Freitas Melo;George Gardner Brown;Priscila Luzia Simon;Mariana Alves Ibarr;L. Cunha;P. Kille
中科院分区：
文献类型：
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作者：
Bruna Ramalho;J. Dieckow;Vander de Freitas Melo;George Gardner Brown;Priscila Luzia Simon;Mariana Alves Ibarr;L. Cunha;P. Kille
近年来，人为暗土被认为是前哥伦布民族进行可持续土壤管理做法的典范。然而，与通常强调热源结构的作用相比，人们对矿物-有机缔合在这些土壤中有机质储存中的作用知之甚少。我们量化了碳和氮的变化及其在ADEs物理组分中的分布与参考(相邻)土壤的关系。在巴西亚马逊地区选择了四个ADES地点，它们具有不同的土壤质地类别，即沙质粘土、沙质粘土、粘土和极粘土。从0-10 cm土层采集土壤样本，将样本的一个子集分离为大团聚体(<；500μm)和小团聚体(<；500μm)。ADE平均储存的总有机碳(TOC)和总氮(TN)比对照土壤多45%和44%。在ADE中增加的TOC和TN中，粉粒平均储存了TOC和TN的92%和37%，C/N比高达25，这可能表明有热源物质的存在。粘粒组分储存了27-46%的增量TOC和27-66%的增量TN。ADEs粘粒组分的C/N值平均为10.5，低于参照土粘粒组分的C/N值(平均值11.1)，说明ADEs粘粒组分的有机质主要来源于微生物，而不是热源。因此，我们得出结论，粘粒是这些人为土中TOC和TN积累和稳定的重要部位，可能是通过矿物-有机缔合机制。
The anthropogenic dark earths (ADEs) are being assumed in recent years as a model representing the result of sustainable soil management practices carried out by Pre-Columbian peoples. However, little is known about the role of mineral-organic associations in organic matter storage in those soils compared to the emphasis generally given to the role of pyrogenic structures. We quantified the changes of carbon and nitrogen and their distribution in physical fractions of ADEs in relation to the reference (adjacent) soil. Four ADEs sites having the different soil textural classes of sandy clay loam, sandy clay, clayey, and very clayey were selected in the Amazon region of Brazil. Soil samples were collected from the 0–10 cm layer and a subset of the sample was separated into large aggregates (>500 μm) and small aggregates (<500 μm). The ADEs stored on average 45% more total organic carbon (TOC) and 44% more total nitrogen (TN) than the reference soils. Of the incremental TOC and TN in ADE relative to the reference soil, the silt size fraction stored on average 92% of this TOC and 37% of this TN and had C:N ratios as high as 25, which may indicate the presence of pyrogenic material. The clay fraction stored a substantial share of 27–46% of the incremental TOC and 27–66% of the incremental TN. The C:N ratio in the clay size fraction of ADEs, on average 10.5, was lower or not different than in the clay fraction of reference soil (average of 11.1), indicating that the organic matter in the clay fraction even of ADEs was predominantly of microbial origin, and not pyrogenic. We therefore conclude that the clay fraction proved to be an important location to the accumulation and stabilization of TOC and TN in these Anthrosols, possibly by mineral-organic association mechanisms.