Origin of Subsoil Carbon in a Chinese Paddy Soil Chronosequence
Origin of Subsoil Carbon in a Chinese Paddy Soil Chronosequence
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DOI：
10.1017/s0033822200058197
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发表时间：
2013-05
期刊：
影响因子：
8.3
通讯作者：
T. Bräuer;P. Grootes;M. Nadeau
中科院分区：
文献类型：
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作者：
T. Bräuer;P. Grootes;M. Nadeau
稻田是非常重要的农业土壤，因为它们是世界上主要的主粮提供者，并且由于特殊的管理实践而在全球碳循环中发挥着关键作用。对中国浙江省填海河口沉积物上形成的由稻田和旱地土壤组成的土壤年代序列进行了采样，以研究农业利用时间（50 至 2000 年）对土壤成分的影响。母质成分的均匀性提供了独特的机会，可以使用加速器质谱 (AMS) 进行的 14C 测量来比较不同土地管理措施（稻田和非稻田）对土壤碳动态以及表土和底土中有机碳 (OC) 来源的影响。土壤总有机碳（TOC）被分成不同迁移率的化学定义库，即酸溶性和水溶性黄腐酸（FA）、碱溶性腐殖酸（HA）和不溶性胡敏素部分。流动性更强的 HA 和 FA 部分比相应的 TOC 和胡敏素含有更多的 14C，表明 OC 在底土中向下传输。植物根部 14C 浓度高达现代标准的 128%（远低于犁盘），表明植物根部和根系分泌物是稻田土壤中底土 OC 的其他直接来源。
Rice paddies are highly important agricultural soils in view of their relevance as major staple food provider in the world and their key role in the global carbon cycle, caused by special management practices. A soil chronosequence, consisting of paddy and upland soils, developed on reclaimed estuarine sediments in the Province of Zhejiang, China, was sampled to investigate the influence of duration of agricultural use (50 to 2000 yr) on soil composition. The uniform composition of the parent material provides the unique opportunity to compare the effects of different land management practices (paddy and non-paddy) on soil carbon dynamics and the origin of organic carbon (OC) in top- and subsoils, using 14C measurements by accelerator mass spectrometry (AMS). The total soil organic carbon (TOC) was split into chemically defined pools of different mobility, namely the acid- and water-soluble fulvic acids (FA), the alkali-soluble humic acids (HA), and insoluble humin fraction. The more mobile HA and FA fractions contain significantly more 14C than the corresponding TOC and humin, indicating a downward transport of OC in the subsoil. Plant roots with 14C concentrations up to 128% of the modern standard, found far below the plough pan, reveal plant roots and root exudates as other direct sources of subsoil OC in paddy soils.