黑土团聚体与颗粒中碳、氮含量及腐殖质组成的比较

Comparison of Carbon, Nitrogen Contents and Humus Compositions in the Aggregates and Particles of Black Soil

【目的】研究黑土不同粒级团聚体和颗粒中的碳、氮及腐殖质组分含量,并分析、比较土壤团聚体与土壤颗粒中腐殖质相互关系。【方法】以黑土区连续9年的耕作试验为平台,采用湿筛法分离土壤团聚体,超声波方法分离土壤颗粒,分别测定不同粒级团聚体和土壤颗粒中的碳、氮、胡敏酸(HA)、富里酸(FA)、铁结合胡敏素(Hi)、黏粒结合胡敏素(Hc)和不溶性胡敏素(Hr)的含量。【结果】>53μm粒级颗粒中的碳、氮以及HA、FA、Hi和Hc的含量明显低于<53μm粒级颗粒,而>53μm和<53μm粒级团聚体中的碳、氮以及HA、FA、Hi和Hc的含量则基本处于同一水平。因此,形成团聚体的过程,弱化了粒级之间有机质的差异。相同粒级比较,在>53μm粒级中,团聚体比颗粒含有更多的腐殖质,且PQ值和腐殖质化程度大于颗粒;但在<53μm粒级中,团聚体和颗粒中腐殖质的含量和PQ值则处于同一水平,说明在较大粒级中,由于同样也包含了小颗粒的作用,强化了团聚体与颗粒中有机质的差异。【结论】土壤团聚体与土壤颗粒中碳、氮以及腐殖质各组分含量随粒级变化的规律存在着明显差异。不同粒级土壤颗粒中有机质的含量差异及其腐殖化程度差异会随着团聚化作用减弱。

[Objective] The objective of this study was to research the contents of carbon, nitrogen and humus composition in different aggregates and particle-size fractions of black soil, to analyze and compare the relationship of humus in the soil aggregate and particle-size fractions. [Method] The research platform was an 9-years field experiment carried out in black soil region, and soil aggregates and particles were separated by wet sieving and ultrasonic method, respectively. The contents of total C, N, the composition of humic substance （HS） in soil aggregates and particle-size fractions, were investigated respectively. [Result] The contents of C, N, humic acid （HA）, fulvic acid （FA）, iron-combined humin （Hi） and cly-combined humin （Hc） were much lower in 〉53 μm particle-size fractions than those in 〈53 μm particle-size fractions while the contents of C, N, HA, FA, Hi and Hc in 〉53 μm aggregates were at the same level as those in 〈53 μm aggregates. Therefore, the process of aggregation reduced the difference of humic substance in different particle-size fractions. Compared the aggregates with particle-size fractions at the same size, the aggregates contained more humic substance in 〉53 μm fractions than particle-size fractions, in addition, the PQ and humification degree of HS in aggregates were higher than that in particle-size fractions. In 〈53 μm fractions, however, the contents of humic substance and PQ in aggregates and in particle-size fractions were at the same level. This shows that for 〉53 μm fractions, the differences of humic substance in aggregates and particle-size fractions increased because 〉53 μm aggregates contained small particle-size fractions. [Conclusion] The regularity of C, N contents and quantities of humic substance in soil aggregates withdifferent diameters were quite different from that in particle-size fractions. The differences of humus content and humification degree in particles will be weakened during the process of aggregating.