同步辐射软X射线近边吸收谱方法研究长期施肥对黑土有机碳官能团的影响

以定位20年的黑土肥料试验为平台，利用同步辐射软X射线近边吸收谱(C-1s NEXAFS)方法，研究了长期施用化肥以及化肥配施玉米秸秆对土壤有机碳官能团的影响。结果表明：与不施肥的空白处理(CK)相比，单施化肥(N，NPK)后土壤的芳香C和羧基C含量增加，脂族C和羰基C含量下降，脂族C/芳香C比值降低;与单施化肥处理相比，化肥配施玉米秸秆后芳香C含量下降而脂族C含量增加，脂族C/芳香C比值增加，并随玉米秸秆用量增加表现的更为明显;无论配施玉米秸秆与否，NPK肥混施处理的芳香C、脂族C以及脂族C/芳香C比值均高于单施N肥处理。上述结果说明，单施化肥比不施肥使土壤有机碳官能团中芳香类化合物的相对比例增加，而脂肪烃类化合物的相对比例下降;化肥配施玉米秸秆则比单施化肥增加了脂肪烃类化合物的相对比例，配施高量比低量玉米秸秆的增加趋势更为明显，同时NPK肥混施比单施N肥有利于提高脂肪烃类化合物的相对比例。C-1s NEXAFS方法能够原位表征长期定位施肥条件下土壤有机碳官能团组成的变化。

Effects of Long-Term Fertilization on Organic Carbon Functional Groups in Black Soil as Revealed by Synchrotron Radiation Soft X-Ray Near-Edge Absorption Spectroscopy

A 20 years (1984—2004) stationary field experiment was conducted to evaluate the effects of long-term application of chemical fertilizers (N or NPK) alone or in combination with low (0.125 kg·hm-2) or high dose of corn stalk (0.25 kg·hm-2) on organic carbon functional groups in black soil using synchrotron radiation soft X-ray near-edge absorption spectroscopy (C-1s NEXAFS). Compared with the control (CK) treatment, the aromatic C and the carboxyl C of soil increased, whereas the aliphatic C, the carbonyl C and the aliphatic C/aromatic C ratio decreased after the application of chemical fertilizer alone. After the application of chemical fertilizations in combined with corn stalk, the aromatic C decreased while the aliphatic C and the aliphatic C/aromatic C ratio increased as compared to N or NPK fertilizer treatment. And the change tendency was more obvious with the increase in the dose of corn stalk applied. Regardless of corn stalk application, the aromatic C, the aliphatic C, and the aliphatic C/aromatic C ratio were all higher for NPK than for N fertilizer treatment. The above results indicated that, compared with the no-fertilizer control treatment, the application of chemical fertilizers alone resulted in the relative proportion of aromatic compounds increased whereas that of aliphatic hydrocarbon compounds decreased. On the other hand, the relative proportion of the aliphatic hydrocarbon compounds was higher after the application of chemical fertilizers with than without corn stalk, with high than with low dose of corn stalk, and with NPK than with N fertilization. C-1s NEXAFS spectroscopy could characterize in situ the changes of organic carbon functional groups in soil under long-term stationary fertilization.