黄土区几种土壤培养过程中可溶性有机碳、氮含量及特性的变化

VARIATION OF CONTENT AND STRUCTURAL CHARACTERISTICS OF DISSOLVED ORGANIC CARBON AND NITROGEN IN SOLUBLE ORGANIC MATTER DURING MINERALIZATION OF SEVERAL SOILS IN THE LOESS REGION

对不同地域农田和林地土壤进行35 d好气培养研究,结果表明:不同土壤培养过程中可溶性有机碳(SOC)含量呈明显下降,而可溶性有机氮(SON)含量却呈明显增加趋势。不同农田土壤相比,在培养起始时和培养过程中红油土SOC和SON的平均含量均高于黑垆土和淋溶褐土;同为黑垆土,林地土壤SOC和SON含量均明显高于相应农田土壤。与起始值相比,土壤培养后提取的可溶性有机物的UV280和HIXem(Hu-mification index)值均明显增加,其中HIXem值在培养的第8天和第35天时呈显著增加趋势。随着培养过程的持续,SOC/SON比值逐渐下降。相关分析发现,培养第35天时SOC的减少幅度与UV 280增加比例呈显著正相关;培养第8天时SOC的减少比例与起始HIXem值呈显著负相关。说明UV280和HIXem值可以在一定程度上反映可溶性有机物种类和结构特性的变化。

Soil samples, collected from farmlands and woodlands in different areas of the Loess Plateau, were incubated aerobically in the lab for 35 days. Results show that the concentration of soluble organic carbon （SOC） in the samples decreased, while the concentration of soluble organic nitrogen （SON） increased significantly during incubation. Typ-Eum-Orthic Anthrosols was much higher than Typic Hapli-Ustic Argosols and Typ-Isohumosols in SOC and SON at the beginning of and throughout the incubation. In the case of Typ-Ishumisols, woodland was significantly higher than farmland in SOC and SON. Incubation significantly increased UV280 and HIXom values of soluble organic matter. The rising trend of the latter was especially significant on the 8th day and the 35th day. The SOC/SON ratio of the samples gradually declined with the incubation going on. It was discovered through correlation analysis that the increase in UV280 value was positively correlated with the decrease in SOC on the 35th day, and that remarkable negative relationship between initial HIXem and the decrease in SOC on the 8th day, which suggests that UV280 and HIXem are suitable indicators that may to a certain extent reflect changes in types and structures of SOM in the soil.