中文摘要：

运用元素分析和红外光谱分析法研究了培养条件下添加玉米秸秆对黑土及其大团聚体（〉2 000μm和2 000-250μm）、微团聚体（250-53μm）和粉粒＋黏粒组分（〈53μm）中胡敏酸（HA）数量和结构特征的影响。结果表明：添加玉米秸秆增加黑土及其各级团聚体HA数量,且2 000-250μm大团聚体中HA含量最多;大团聚体HA的氧化度和芳香-C提高;250-53μm微团聚体与〈53μm粉粒＋黏粒HA的氧化度和芳香-C降低;黑土及其各级团聚体HA分子缩合度下降,脂族链烃-C增加,脂族链烃-C/羧基-C和脂族链烃-C/芳香-C值均较对照增加,脂族性得到提高。不同粒级团聚体之间相比,大团聚体中HA分子结构是以高的缩合度、氧化度、脂族链烃-C、芳香-C含量为特征;〈53μm粉粒＋黏粒中HA分子结构是以最低的脂族链烃-C、芳香-C、羧基-C和最高的多聚糖-C为特征。添加玉米秸秆增加了土壤HA数量,降低了HA分子结构的缩合度和氧化度,脂族性提高,使土壤HA分子结构＂年轻化＂,活性增强,对于土壤固碳、提高土壤质量具有重要作用。

英文摘要：

An incubation experiment was conducted to study the effects of corn stalk addition on content and structure characteristics of humic acid（ HA） extracted from black soil and macroaggregates（ 2 000 μm and 2 000 - 250 μm）,microaggregates（ 250 - 53 μm） and silt-clay fractions（ 53 μm） in black soil by using element analysis and Fourier transformed infrared spectroscopy. The results showed that content of HA from bulk soil and different aggregate fractions increased after the addition of corn stalk and the highest HA content was found in 2 000 - 250 μm macroaggregates. Oxidation degree and aromatic-C content of HA from macroaggregates enhanced,and that from the microaggregates and silt-clay fractions declined. For HA in bulk soil and different aggregates,condensation degree reduced whereas aliphatic hydrocarbon-C content,ratio of aliphatic hydrocarbon-C to carboxyl-C and aliphatic hydrocarbon-C to aromatic-C of HA increased,indicating that aliphaticityof HA increased after corn stalk application into the soil. Compared among aggregates,HA from the macroaggregates was characterized with higher degree of condensation and oxidation,content of aliphatic hydrocarbon-C and aromatic-C,whereas HA from the microaggregates and silt-clay fractions was characterized with the lowest content of aliphatic hydrocarbon-C,aromatic-C,carboxyl-C and the highest polysaccharide-C. After corn stalk application into the soil,increase of HA content,decline of degree of condensation and oxidation and enhancement of aliphaticity show that HA tends to be younger and HA activity improves,which plays an important role in carbon sequestration and soil quality improvement.