National Engineering Laboratory for Improving Quality of Arable Land, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
National Engineering Laboratory for Improving Quality of Arable Land, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
Sci Total Environ. 2020 Jun 25;723:138181. doi: 10.1016/j.scitotenv.2020.138181. Epub 2020 Mar 24.
Long term fertilization may have a significant effect on soil organic carbon (SOC) fractions and profile distribution. However, previous research mostly explored the SOC in the topsoil and provided little or no information about its distribution in deeper layers and various protection mechanisms particularly under long-term fertilization. The present study investigated the contents and profile distribution (0-100 cm) of distinct SOC protection mechanisms in the Mollisol (black soil) of Northeast China after 35 years of mineral and manure application. The initial Organic Matter content of the topsoil (0-20 cm) ranged from 26.4 to 27.0 g kg soil, and ploughing depth was up to 20 cm. A combination of physical-chemical fractionation methods was employed to study various SOC fractions. There were significant variations throughout the profile among the various fractions and protection mechanisms. In topsoil (to 40 cm), mineral plus manure fertilization (MNPK) increased the total SOC content and accounted for 16.15% in the 0-20 cm and 12.34% in the 20-40 cm layer, while the manure alone (M) increased the total SOC by 56.14%, 48.73% and 27.73% in the subsoil (40-60, 60-80 and 80-100 cm, respectively). Moreover, MNPK and M in the topsoil and subsoil, respectively increased the unprotected coarse particulate organic carbon (cPOC) (48% and 26%, respectively), physically protected micro-aggregate (μagg) (20% and 18%, respectively) and occluded particulate organic carbon (iPOC) contents (279% and 93%, respectively) compared with the control (CK). A positive linear correlation was observed between total SOC and the cPOC, iPOC, physico-biochemically protected NH-μSilt and physico-chemically protected H-μSilt (p < 0.01) across the whole profile. Overall, physical, physico-biochemical and physico-chemical protection were the predominant mechanisms to sequester carbon in the whole profile, whereas the biochemical protection mechanisms were only relevant in the topsoil, thus demonstrating the differential mechanistic sensitivity of fractions for organic carbon cycling across the profile.
长期施肥可能会对土壤有机碳（SOC）的各个组分及其剖面分布产生显著影响。然而，以往的研究大多集中于表层土壤的 SOC，对其在更深层次的分布以及各种保护机制（特别是在长期施肥下）的了解甚少或几乎没有。本研究在东北黑土（黑钙土）中，经过 35 年的矿质和有机肥施用，调查了不同 SOC 保护机制的含量及其剖面分布（0-100 cm）。表层土壤（0-20 cm）的初始有机质含量范围为 26.4-27.0 g kg-1 土壤，耕层深度达 20 cm。采用物理化学分组方法研究了各种 SOC 组分。在整个剖面中，各组分和保护机制之间存在显著差异。在表层土壤（0-40 cm）中，矿质加有机肥（MNPK）施肥增加了总 SOC 含量，在 0-20 cm 层中占 16.15%，在 20-40 cm 层中占 12.34%，而单独施用有机肥（M）则分别使底层（40-60、60-80 和 80-100 cm）的总 SOC 增加了 56.14%、48.73%和 27.73%。此外，MNPK 和 M 分别增加了表层和底层的非保护粗颗粒有机碳（cPOC）（分别增加 48%和 26%）、物理保护微团聚体（μagg）（分别增加 20%和 18%）和封闭颗粒有机碳（iPOC）含量（分别增加 279%和 93%），与对照（CK）相比。整个剖面中，总 SOC 与 cPOC、iPOC、理化保护的 NH-μSilt 和理化保护的 H-μSilt 之间存在显著的线性正相关关系（p < 0.01）。总的来说，物理、理化生物和理化保护是整个剖面中固碳的主要机制，而生化保护机制仅与表层土壤有关，这表明各组分对有机碳循环的机制敏感性在整个剖面上存在差异。
