Distribution of organic carbon in physical fractions of soils as affected by agricultural management
Distribution of organic carbon in physical fractions of soils as affected by agricultural management
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DOI：
10.1007/s00374-010-0459-7
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发表时间：
2010-08-01
影响因子：
6.5
通讯作者：
Lal, Rattan
中科院分区：
文献类型：
--
作者：
Jagadamma, Sindhu;Lal, Rattan
土壤有机碳（SOC）不均匀地分布在不同尺寸的初级颗粒和团聚体之间。此外，与不同物理部分相关的 SOC 对管理的响应也不同。因此，本研究的目的是量化受长期管理变化影响的 SOC 的所有三个结构水平（颗粒有机物、土壤分离物和聚集体尺寸部分）相关的 SOC。该研究还旨在重新评估单个尺寸部分的 SOC 汇容量有限的概念。对于俄亥俄州伍斯特的混合、中性、典型 Fragiudalf，将长期耕作和轮作对各部分 SOC 分布的影响与邻近未受干扰地区本地植被下的土壤进行了比较。四十五年的免耕 (NT) 管理导致土壤表面 (0-7.5 厘米) 的 SOC 积累量高于凿耕和犁耕 (PT) 处理。然而，该地点的 PT 导致 SOC 从表层土壤重新分布到更深的土壤层。在 7.5-45 cm 深度，连作玉米土壤积累的 SOC 显着高于玉米-大豆轮作土壤。尽管土壤质地主要由粉砂大小的颗粒主导，但大部分 SOC 库与粘土部分相关。与 PT 相比，NT 处理导致 (i) 大团聚体 (> 2,000 μm) 的比例显着更高，并且 (ii) 所有团聚体尺寸类别中的 SOC 浓度高出 1.5-2.8 倍。使用雷达图进行的比较评估表明，在物理部分中，与沙子和淤泥部分相关的 SOC 随着土地利用从原生植被向农作物的转变而迅速变化。这项研究的一个重要发现是对各个部分的 SOC 汇能力的评估，结果表明农业土壤的粘土部分继续积累更多的 SOC，尽管速度较慢，但总 SOC 浓度逐渐增加。然而，原生林下土壤的粘土部分显示出 SOC 饱和的迹象。本研究中提供的来自 SOC 所有三个结构层面的数据将有助于完善当前土壤有机质预测模型的概念池定义。
Soil organic carbon (SOC) is distributed heterogeneously among different-sized primary particles and aggregates. Further, the SOC associated with different physical fractions respond differently to managements. Therefore, this study was conducted with the objective to quantify the SOC associated with all the three structural levels of SOC (particulate organic matter, soil separates and aggregate-size fractions) as influenced by long-term change in management. The study also aims at reevaluating the concept that the SOC sink capacity of individual size-fractions is limited. Long-term tillage and crop rotation effects on distribution of SOC among fractions were compared with soil from adjacent undisturbed area under native vegetation for the mixed, mesic, Typic Fragiudalf of Wooster, OH. Forty five years of no-till (NT) management resulted in more SOC accumulation in soil surface (0-7.5 cm) than in chisel tillage and plow tillage (PT) treatments. However, PT at this site resulted in a redistribution of SOC from surface to deeper soil layers. The soils under continuous corn accumulated significantly more SOC than those under corn-soybean rotation at 7.5-45 cm depth. Although soil texture was dominated by the silt-sized particles, most of the SOC pool was associated with the clay fraction. Compared to PT, the NT treatment resulted in (i) significantly higher proportion of large macroaggregates (> 2,000 mu m) and (ii) 1.5-2.8 times higher SOC concentrations in all aggregate-size classes. A comparative evaluation using radar graphs indicated that among the physical fractions, the SOC associated with sand and silt fractions quickly changed with a land use conversion from native vegetation to agricultural crops. A key finding of this study is the assessment of SOC sink capacity of individual fractions, which revealed that the clay fraction of agricultural soils continues to accumulate more SOC, albeit at a slower rate, with progressive increase in total SOC concentration. However, the clay fraction of soil under native woodlot showed an indication for SOC saturation. The data presented in this study from all the three structural levels of SOC would be helpful for refining the conceptual pool definitions of the current soil organic matter prediction models.