氮添加对白羊草土壤水溶性碳氮及其光谱特征的影响

大气氮沉降对土壤的影响已成为近年来的研究热点,为了解氮沉降对黄土高原典型草原土壤质量的影响,以白羊草群落为研究对象,以氮添加的方式模拟氮沉降,选取3个氮添加梯度,分别为N1(2.5g/m~2),N2(5g/m~2)和N3(10g/m~2),并选取裸地(BL)和不施氮(CK)作为对照处理,分析了对土壤水溶性碳、氮组分及其光谱学特征的影响。结果表明,氮添加降低了WSOC/TOC和WSOC含量,随着氮添加水平增加均呈降低趋势;而对水溶性氮素组分影响较弱,仅在N2中WSN和WSON显著降低,对WS-NH+4-N,WS-NO-3-N和WSON/WSN没有显著影响。氮添加对土壤水溶性有机物质光谱特性影响显著,紫外可见光谱和荧光发射光谱分析均表明土壤水溶性有机物的主要腐殖质类型均为富里酸,随着施氮水平的增加腐殖化程度增强,结构趋于复杂化。

Effects of Nitrogen Addition on Dissolved Matter and Spectroscopic Characteristics of Soil Growing Bothriochloa ischaemum

The effect of atmospheric nitrogen deposition on soil has been the research hotspot in recent years.In order to study the effects of nitrogen deposition on soil quality of typical grassland in the Loess Plateau,a simulated nitrogen deposition was conducted with the method of nitrogen addition into the Bothriochloa ischaemum community.The four nitrogen addition gradients were CK (0 g/m2),N1 (2.5 g/m2),N2 (5 g/m2),N3 (10 g/m2),and the bare land (BL) was also selected as the control.The results showed that N addition decreased the contents of WSOC/TOC and WSOC,with the increase of N level,the trend decreased,but the effect of N addition on water soluble nitrogen was weak,only WSN and WSON significantly decreased in N2 treatment,no significant effect on WS-NH4+-N,WS-NO3--N and WSON/WSN was observed.Moreover,the effect of N addition on the spectral characteristics of soil water soluble organic matter was significant,the UV visible spectrum and the fluorescence emission spectrum showed that the main humus types of soil water soluble organic matter were fulvic acid,with the increase of nitrogen application,the humification degree increased and the structure became more complex