Soil organic carbon mineralization rates in aggregates under contrasting land uses
Soil organic carbon mineralization rates in aggregates under contrasting land uses
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DOI：
10.1016/j.geoderma.2013.10.023
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发表时间：
2014-03
期刊：
影响因子：
6.1
通讯作者：
S. Rabbi;B. Wilson;B. Wilson;P. Lockwood;H. Daniel;I. Young
中科院分区：
文献类型：
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作者：
S. Rabbi;B. Wilson;B. Wilson;P. Lockwood;H. Daniel;I. Young
测定土壤大团聚体（250-2000 μm）、微团聚体（250-53 μm）和< 53 μm团聚体中有机碳（SOC）矿化有助于了解土壤团聚体中SOC的空间分离如何调节其动态。研究结果表明：（1）与大团聚体相比，微团聚体的SOC矿化速率较慢;（2）< 53 μm颗粒对SOC的吸附降低了SOC的矿化速率;（3）土地利用方式对SOC的分解速率有显著影响。为了验证这些假设，我们收集了表土Dermosol（Acrisols在粮农组织土壤分类）网站下三个对比的土地利用，即天然牧场（NP），作物-牧场轮作（CP）和林地（WL）。通过湿筛分法将大团聚体、微团聚体和< 53 μm团聚体从土壤中分离出来。然后将三种聚集体尺寸范围孵育六个月，并在不同的时间间隔测量CO2释放。通过用10%H2O2氧化SOC来测量大团聚体、微团聚体的< 53 μm级分和< 53 μm级分（通过湿筛分离）的化学稳定SOC。平均而言，< 53 μm的部分的累积矿化Cmin（g CO2-C kg− 1聚集体）比大聚集体和微聚集体低28%。然而，SOC矿化（SOCmin）是相似的，在所有的大小级分。缓慢SOC池的大小（SOC浓度在团聚体中的百分比）在< 53 μm的部分中也显著较高，并且在不同团聚体大小的范围内从58%到96%。而大团聚体和微团聚体中的化学稳定性SOC（占团聚体中SOC浓度的百分比）显著高于< 53 μm团聚体。慢SOC池（MRT）的平均停留时间（MRT）在< 53 μm的级分中高于大聚集体或微聚集体。在土地利用中，NP的最小土壤有机碳浓度高于CP和WL。结果表明，大团聚体和微团聚体的最小SOC、慢速SOC库大小和MRT值差异不显著，说明大团聚体和微团聚体的SOC矿化速率和对SOC的保护作用相似。
Measuring soil organic carbon (SOC) mineralization in macro-aggregates (250–2000 μm), micro-aggregates (250–53 μm) and the < 53 μm fraction helps to understand how spatial separation of SOC inside soil aggregates regulates its dynamics. We hypothesized that (i) compared with macro-aggregates SOC mineralization rate of micro-aggregates would be slower, (ii) adsorption of SOC on < 53 μm fraction decreases the SOC mineralization rate, and (iii) land use has a significant influence on SOC decomposition rate. To test these hypotheses we collected topsoil from Dermosol (Acrisols in FAO Soil Classification) sites under three contrasting land uses namely native pasture (NP), crop–pasture rotation (CP) and woodland (WL). Macro-aggregates, micro-aggregates and the < 53 μm fraction were separated from bulk soil by wet sieving. The three aggregate size ranges were then incubated for six months and CO2evolution was measured at different time intervals. The chemically stable SOC of < 53 μm fraction of macro-aggregates, micro-aggregates and the < 53 μm fraction (separated by wet sieving) was measured by oxidation of SOC with 10% H2O2. On average, cumulative mineralization, Cmin(g CO2–C kg− 1aggregate) of the < 53 μm fraction, was 28% lower than that of macro-aggregates and micro-aggregates. However, SOC mineralized (SOCmin) was similar in all size fractions. The size of slow SOC pool (percent of SOC concentration in aggregates) was also significantly higher in the < 53 μm fraction and ranged from 58 to 96%, across aggregate sizes. However, the chemically stable SOC (percent of SOC concentration in aggregates) was significantly higher in macro-aggregates and micro-aggregates than that of the < 53 μm fraction. Mean residence time (MRT) of slow SOC pool (MRTs) was higher in the < 53 μm fraction than for either macro-aggregates or micro-aggregates. Among the land uses NP had higher SOCmincompared with CP and WL. In conclusion, the insignificant difference in SOCmin, slow SOC pool sizes and MRTsbetween macro-aggregates and micro-aggregates indicated that SOC mineralization rate and thus the protection of SOC was similar in both macro-aggregates and micro-aggregates.