Total, hot water extractable, and oxidation-resistant carbon in sandy hydromorphic soils-analysis of a 220-year chronosequence
Total, hot water extractable, and oxidation-resistant carbon in sandy hydromorphic soils-analysis of a 220-year chronosequence
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DOI：
10.1007/s11104-010-0322-5
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发表时间：
2010
期刊：
影响因子：
4.9
通讯作者：
M. Spohn;L. Giani
中科院分区：
文献类型：
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作者：
M. Spohn;L. Giani
土壤有机碳储量在从牧场转作农田后减少。人们一直认为，这一点尤其适用于矿物水成土。在本文中，我们评估了热水可提取碳(CHWE)作为一种检测土地利用变化后土壤有机质长期变化的指标。此外，我们评估了用NaOCl处理土壤是否会导致长期稳定的C组分的分离。为此，我们建立了不同历史时期从牧场转化为农田的沙质水相土壤的年代序列。为了进一步了解不同类型的土地利用对碳固定的影响，对森林下的土壤进行了研究，无论是绿化的还是永久的。对72个潮土和半夏土表层土壤的容重、总有机碳(TOC)、Chwe和抗NaOClC进行了定量研究。在退耕还草后的前25年，土壤容重从0.9g/cm−3增加到1.4g/cm−3。永久牧场的总有机碳浓度为35.4(±12.1)g/kg−1，开垦后的头46年降至12.88(±5.9)g/kg−1(R2= 0.71)。在永久性森林土壤中，TOC浓度显着高于已造林土壤。时间序列站点的ChWE浓度与TOC浓度呈线性相关(R2= 0.84)，而永久森林站点的CHWE/TOC比值明显较高。这表明，Chwe值的测定是检测造林后土壤有机质动态变化的一种非常有前途的方法。在永久牧场，测得14.3(±5.38)g/kg−-1NaOCl抗性C，而46年后，仅剩下2.8(±1.2)g/kg−-1。在时间序列中没有观察到抗NaOCl的C的富集，因为在培养过程中抗NaOCl的C的下降速度快于TOC。因此，我们得出结论，在土壤中，抵抗NaOCl氧化的C组分不是长期稳定的，很可能在所研究的土壤中不存在这种长期稳定的C组分。
Soil organic carbon stocks decrease after conversion of soils from pasture to cropland. It has been assumed that this applies especially to mineral hydromorphic soils. In this paper we evaluate hot-water extractable carbon (Chwe) as a measure for detecting long-term changes in the SOM following land use change. Furthermore, we assess whether a treatment of the soils with NaOCl leads to the isolation of long-term stable C fractions. For these purposes, we established a chronosequence of sandy hydromorphic soils that have been converted from pasture to cropland at different periods of history. To gain further insight into the impacts of different types of land use on carbon sequestration, soils under forest, either afforested or permanent, were studied. Bulk density, total organic carbon (TOC), Chwe, and NaOCl-resistant C were quantified in the surface soils of 72 Gleyic Podzols and Haplic Gleysols. The bulk density increased from 0.9 (±0.2) g cm−3to 1.4 (±0.1) g cm−3during the first 25 years after the conversion of the soils from permanent pasture to cropland. In the permanent pasture sites, the TOC concentration amounted to 35.4 (±12.1) g kg−1. It decreased to 12.88 (±5.9) g kg−1during the first 46 years of cultivation (R2= 0.71). In the permanent forest soils the TOC concentrations were significantly higher than in the soils that have been afforested. Chweconcentrations of the chronosequence sites were linearly correlated to the TOC concentrations (R2= 0.84), while permanent forest sites exhibited significantly higher Chwe/TOC ratios. This shows that the determination of the Chweis a very promising measure for detecting changes in SOM dynamics following afforestation. In the permanent pasture sites, 14.3 (±5.38) g kg−1NaOCl-resistant C was measured, while 46 years after conversion, only 2.8 (±1.2) g kg−1remained. No enrichment of NaOCl-resistant C was observed in the chronosequence, as NaOCl-resistant C decreased faster in the course of cultivation than the TOC. Therefore, we conclude that that the C fraction that resists the oxidation with NaOCl is not long-term stable in soils, and most probably, there is no such long-term stable C fraction in the soils under study.