Organic carbon accumulation in a 2000-year chronosequence of paddy soil evolution
Organic carbon accumulation in a 2000-year chronosequence of paddy soil evolution
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DOI：
10.1016/j.catena.2011.07.007
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发表时间：
2011-12
期刊：
影响因子：
6.2
通讯作者：
L. Wissing;A. Kölbl;V. Vogelsang;Jian-rong Fu;Z. Cao;I. Kögel‐Knabner
中科院分区：
文献类型：
--
作者：
L. Wissing;A. Kölbl;V. Vogelsang;Jian-rong Fu;Z. Cao;I. Kögel‐Knabner
相当数量的土壤有机质在水稻土中是稳定的，因此很大比例的陆地碳在湿地水稻土中被保存。然而，水稻土中有机碳(OC)的稳定机制在很大程度上是未知的。基于海洋沉积物的时间序列，本研究的目的是研究有机碳的积累和无机碳(IC)的同时损失，并确定随着水稻土管理时间的延长，土壤组分对有机碳稳定的作用。本文选取了浙江省稻田土壤形成的6个年龄组(PR中国)，时间跨度为50~2000年。对每个年龄段内三个土壤剖面的水平采样获得的土壤样品进行了容重(BD)、有机碳(OC)和IC浓度、散体土壤的有机碳储量以及颗粒组分对散体土壤的有机碳贡献的分析。水田土壤的特征是，淤泥表土层的容重相对较低(1.0gcm和1.2gcm−3)，而犁土层的容重较高(1.6gcm−3)。我们的结果表明，在土壤形成过程中碳酸盐的大量损失，因为在100年前的水稻土中，表层20厘米没有碳酸盐，但从整个土壤剖面中去除碳酸盐需要近700年的水稻栽培。我们观察到，在稻田管理的50到2000年间，表土有机碳储量从2.5kgm−2增加到4.4kgm。有机碳在土壤中的积累主要以粉粒级和粘粒级分为主。粉质组分表现出有机碳的高吸积性，似乎是土壤演化过程中一个重要的长期有机碳汇。淤泥表土层中的细粒粘土已经饱和，粗粘土的有机碳储存量最大。随着稻田管理时间的延长，20μm组分的实际有机碳饱和度有所增加，但没有达到计算的潜在库容。
Considerable amounts of soil organic matter (SOM) are stabilized in paddy soils, and thus a large proportion of the terrestrial carbon is conserved in wetland rice soils. Nonetheless, the mechanisms for stabilization of organic carbon (OC) in paddy soils are largely unknown. Based on a chronosequence derived from marine sediments, the objectives of this study are to investigate the accumulation of OC and the concurrent loss of inorganic carbon (IC) and to identify the role of the soil fractions for the stabilization of OC with increasing duration of paddy soil management. A chronosequence of six age groups of paddy soil formation was chosen in the Zhejiang Province (PR China), ranging from 50 to 2000years (yrs) of paddy management. Soil samples obtained from horizontal sampling of three soil profiles within each age group were analyzed for bulk density (BD), OC as well as IC concentrations, OC stocks of bulk soil and the OC contributions to the bulk soil of the particle size fractions. Paddy soils are characterized by relatively low bulk densities in the puddled topsoil horizons (1.0 and 1.2gcm−3) and high values in the plow pan (1.6gcm−3). Our results demonstrate a substantial loss of carbonates during soil formation, as the upper 20cm were free of carbonates in 100-year-old paddy soils, but carbonate removal from the entire soil profile required almost 700yrs of rice cultivation. We observed an increase of topsoil OC stocks from 2.5 to 4.4kgm−2during 50 to 2000yrs of paddy management. The OC accumulation in the bulk soil was dominated by the silt- and clay-sized fractions. The silt fraction showed a high accretion of OC and seems to be an important long-term OC sink during soil evolution. Fine clay in the puddled topsoil horizon was already saturated and the highest storage capacity for OC was calculated for coarse clay. With longer paddy management, the fractions <20μm showed an increasing actual OC saturation level, but did not reach the calculated potential storage capacity.