Dissolved organic matter (DOM) is the most active component of organic materials, which plays a crucial role in soil organic matter accumulation and soil manuring during the decomposition. We conducted a five-site (Changtu of Liaoning, Dehui of Jilin, Harbin, Hailun and Heihe of Heilongjiang) in-situ experiment with six different organic materials (chicken manure, pig manure, fungal bran, soybean straw, maize straw and rice straw), in Northeast China's black soil belt from south to north. We aimed to characterize the DOM properties by spectroscopic techniques and to uncover the influencing factors. Results showed that after a two-year decomposition, the dissolved organic carbon concentration decreased notably, while the aromaticity index, content of hydrophobic fraction, concentration of colored dissolved organic matter and humification index of the organic materials increased, and differed among the organic materials. The fluorescence index values of all DOM were <1.4, and the autochthonous index values ranged 0.4-0.7, showing a characteristics of exogenous input and low bioavailability. Parallel factor analysis revealed that the relative contents of fulvic acid-like and protein-like fractions in organic manure and fungal bran DOM decreased, while the relative content of humus-like fraction increased. For crop straw DOM, there was a significant decrease in the relative content of protein-like fraction. The properties of DOM exhibited regional variations. The aromaticity and humification degree of DOM increased with the increasing cumulative temperature. From Heihe with the lowest accumulated temperature to Changtu with the highest temperature, the aromaticity and humification indexes of DOM increased by 6.9%-42.7% and 23.9%-59.0%, respectively. The properties of DOM of organic materials were significantly influenced by the type of organic materials, experiment site, and their interactions. Principal component and correlation analyses indicated that the characteristics of organic materials DOM after decomposition linked more to their intrinsically chemical structure of organic carbon than to experiment site. In conclusion, after two-year decomposition, the active components within DOM of all the organic materials converted into more stable components, leading to increased aromaticity and humification degree. The inherent characteristics of organic materials was the predominant factor influencing the changes in DOM characteristics.
溶解性有机质(DOM)是有机物料中最活跃的组分,在有机物料还田腐解转化为土壤有机质、培肥土壤过程中发挥重要作用。本研究以东北黑土区为研究区域,在典型黑土带上由南向北选择辽宁省昌图县、吉林省德惠市、黑龙江省哈尔滨市、海伦市和黑河市5个地点,布设6种有机物料(鸡粪、猪粪、木耳菌糠、大豆秸秆、玉米秸秆和水稻秸秆)的田间腐解试验,采用光谱学技术研究有机物料还田腐解后其自身DOM性质的变化及主要影响因素。结果表明: 有机物料腐解2年后,溶解性有机碳浓度显著下降,芳香性指数、疏水性组分含量、有色溶解性有机质浓度和腐殖化指数均不同程度增加,且不同种类有机物料间存在差异。DOM的荧光指数值均<1.4,自生源指数值介于0.4～0.7,外源输入特征明显,生物可利用性较低。平行因子分析发现,腐解后有机粪肥和菌糠DOM中类富里酸和类蛋白质组分的相对含量减少,类腐殖质组分的相对含量增大;作物秸秆DOM中类蛋白质组分的相对含量大幅下降。有机物料腐解后DOM性质具有明显的地带性变化规律,DOM的芳香性和腐殖化程度随试验地点积温的升高而增强,从积温最低的黑河到积温最高的昌图,DOM的芳香性和腐殖化指数分别提高了6.9%～42.7%和23.9%～59.0%。有机物料的种类和试验地点以及二者的相互作用均对DOM性质有显著影响,相关性和主成分分析结果表明,有机物料DOM性质与其自身化学结构密切相关,且受有机物料种类影响较大,受试验地点影响较小。综上,有机物料还田腐解2年后,DOM中活性组分向稳定组分转化,芳香性和腐殖化程度提高,自身性质是影响有机物料腐解中DOM性质变化的主要因素。.
Keywords: organic material; decomposition; dissolved organic matter; spectral characteristics; black soil region of Northeast China.