论文部分内容阅读
选取我国南方三种典型水稻土的长期试验田,采集长期不同处理下的未破坏土壤样品,采用低能量超声波分散法分离得到不同粒径的团聚体颗粒组,研究不同处理下这些团聚体颗粒组中的有机碳(Soil organic carbon,SOC)含量及其分配变化,探讨土壤有机碳积累与团聚体物理保护的关系。结果表明:供试三种水稻土团聚体颗粒组的组成以200~20μm和20~2μm粒径为主,分别占22%~43%和27%~44%,微团聚化作用较强。SOC含量以2 000~200μm和<2μm粒组中最高;而易氧化态碳(Labile organic car-bon,LOC)主要富集于2 000~200μm粗团聚体颗粒组中,其占SOC的比例(LOC/SOC)也是以该粒径中明显最高。直径为2 000~200μm的粗团聚体颗粒组作为新增有机碳的主要载体,随不同耕作和施肥等长期处理的变化最为强烈,其中又以红壤性水稻土的SOC和LOC随不同施肥的变化最为强烈,说明其良好管理下的有机碳累积效应最为显著。统计分析表明,全土的有机碳积累量与2 000~200μm粗团聚体的有机碳积累量之间的关系可用抛物线拟合(R2=0.95,n=8)。由此看来,长期试验下新固定的有机碳积累及其粗团聚体保护可能存在某种饱和机理。计算表明,供试水稻土的粗团聚体保护在长期试验期内还未达到其饱和限,本研究结果支持了我国学者对于近20年来南方水稻土特别是红壤丘陵区水稻土有机碳固定速率较高的认识。同时,红壤性水稻土的粗团聚体保护作用最强,仍然具有明显的固碳潜力,这也提示土壤中氧化铁对水稻土中有机碳的固定和化学稳定可能有重要贡献,水稻土固碳的团聚体保护作用与团聚体中有机碳的化学结合机制有关。
Long-term experimental fields of three types of typical paddy soils in southern China were selected to collect long-term non-destructed soil samples under different treatments. The agglomerate particles with different particle sizes were isolated by low-energy ultrasonic dispersion method. Soil organic carbon (SOC) content and its distribution changes, and to explore the relationship between soil organic carbon accumulation and aggregate physical protection. The results showed that the aggregates of three kinds of paddy soil aggregates were mainly composed of 200 ~ 20μm and 20 ~ 2μm, accounting for 22% ~ 43% and 27% ~ 44%, respectively. The content of SOC was highest in the range of 2 000 ~ 200 μm and <2 μm, while the concentration of LOC was mainly concentrated in the coarse aggregates of 2 000 ~ 200 μm, which accounted for the proportion of SOC LOC / SOC) is also the highest in this particle size. The coarse aggregates with diameter of 2 000 ~ 200 μm were the main carriers of organic carbon. The change of long-term treatments such as tillage and fertilization were the most significant. Among them, SOC and LOC of red paddy soil changed with different fertilization The strongest, indicating that under the good management of organic carbon accumulation effect most significant. Statistical analysis shows that there is a parabolic curve (R2 = 0.95, n = 8) for the relationship between organic carbon accumulation in the whole soil and organic carbon accumulation in the coarse aggregates of 2 000-200 μm. In view of this, there may be some saturation mechanism for the newly fixed organic carbon accumulation and its coarse aggregate protection under long-term tests. The calculated results show that the crude aggregates of the paddy soils tested have not reached the saturation limit in the long-term test period. The results of this study support our scholars to compare the rate of organic carbon fixation of paddy soils in the southern paddy soil, especially the red soil hilly region, over the past 20 years High understanding. At the same time, the coarse aggregates of paddy soil had the strongest protective effect and still had the potential of carbon sequestration. This also suggests that iron oxide may contribute to the fixation and chemical stability of paddy soil. The aggregate protection is related to the chemical binding mechanism of organic carbon in aggregates.