土壤有机质是土壤的重要组成部分, 在土壤肥力、 环境保护、 农业可持续发展等方面都具有重要作用。 腐殖质作为土壤有机质的主体, 对土壤的一系列性质和形态产生影响, 其数量、 组成和性质可以反映一定的成土条件和过程, 是土壤肥力的重要指标。 由于腐殖质分子组成的不确定性, 各种方法均存在一定的局限性, 优化寻求更为准确可靠的腐殖酸表征方法已成为当前研究的热点。 施肥方式改变土壤中胡敏酸的组成与结构, 但短期的影响程度难以用常规的测定技术检测出来。 利用38年的黑土长期定位试验, 通过腐殖质组分HA的分离和纯化, 多种光谱分析方法的联合应用, 从物质结构的角度分析土壤中单施有机肥和有机无机肥配施对黑土HA有机化合物的分子结构变化的影响。 分析显示, M和MNPK施肥处理较CK处理均可提高土壤有机碳和HA含量, 增加土壤中HA的总反应热、 中温放热值、 2920/1720值、 脂族C含量、 f450/500值, 表明单施有机肥和有机无机肥配施后土壤HA芳构化程度降低, 脂族含量增加, 结合简单化, 但M施肥处理增加幅度小于MNPK施肥处理。 分析结果表明: 多种光谱技术的联合应用, 可以相互认证其结果的准确性。 同时试验结果也证明有机无机肥配施较单施有机肥, 更能提高土壤有机碳和土壤HA的脂族C含量, 增加作物产量, 培肥地力。

Soil organic matter is an important part of soil , and plays an important role in soil fertility, environmental protection and sustainable development of agriculture .As the main body of soil organic matter, humus has an effect on a series of properties and forms of soil. Its quantity, composition and properties can reflect certain conditions and processes of soil formation, and it is an important index of soil fertility. Humus is a complex mixture of species, and there is no definite molecular weight and only molecular weight distribution. Its molecular composition and chemical structure are still not clear until now, which largely limits the further research of humic acid. Due to the uncertainty of the composition of the humus molecules, there are some limitations of various methods. Optimizing the search for a more accurate and reliable humic acid characterization method has become a hot spot in the current research. Fertilization modifies the composition and structure of humic acid in soil, but the short-term influence degree is difficult to be detected by conventional methods. This paper uses 38 years of long-term black soil positioning test, through the separation and purification of humic component HA, thermal properties analysis, fourier transform infrared spectroscopy, 13C nuclear magnetic resonance spectroscopy and fluorescence spectroscopy analysis technology. The effects of organic fertilizer and inorganic fertilizer on the molecular structure of HA in black soil were analyzed from the point of view of material structure. The results showed that the mechanism of organic fertilizers application (MNPK) and CK (no fertilization) to increase crop yields was that MNPK fertilization increased soil organic carbon content compared with CK, at the same time, the HA content of humus could be extracted from soil, and the content of aliphatic C in soil HA increased and the structure was simplified. The lipids in soil organic matter were mainly fat, wax and resin, which had a significant influence on the decomposition of soil organic matter, thus affecting nutrient release and plant growth, and the increase of soil nutrients promoted the increase of maize yield under MNPK fertilization. The analysis showed that the total reaction heat of MNPK fertilization treatment soil HA, 2 920/1 720 and 2 920/2 850 value was higher than CK, and 13C nuclear magnetic resonance spectroscopy showed that the molecular structure of HA in black soil was obviously aliphatic after MNPK fertilization, and increased the soil aliphatic C content of HA, reduced the aromatic C content. Fluorescence emission spectra showed that the f450/500 value of MNPK-treated HA increased significantly compared with the control, indicating that the degree of aromatization of soil HA decreased with the application of organic fertilizer. The above analysis results showed that: after the application of organic and inorganic fertilizers, the molecular structure of HA in the black soil became aliphatic and simplistic; the combination of multiple spectroscopic techniques could mutually verify the accuracy of the results. At the same time, the test results also proved that once organic fertilizer was applied in the rotation period, the soil organic carbon and the Aliphatic C content of soil HA could be increased, and the crop yield and soil fertility could be increased.