Abstract: Using nearedge Xray absorption fine structure (NEXAFS) spectrum combined with the quantitative analysis method, we carried on the system analysis to the organic carbon functional groups of albic soil with corn straw based on the application of equal nitrogen amount and different nitrogen forms of n(NH⁺⁴)∶n(NO^-3)=4,1,1∶4. The results show that the addition of nitrogen in any form is helpful to the microbial mineralization of soil organic carbon (SOC) of albic soil with corn straw. The n(NH⁺⁴)∶n(NO^-3)=1 is more advantageous in promoting the mineralization and decomposition of SOC, which is beneficial to the formation and accumulation of fulvic acid extracted from the albic soil, and to enhance its physiological activity of humic acid to a larger degree; the N supply mainly dominated by NO^-3-N is more beneficial to the microbial decomposition and transformation of SOC in a short period of time, and most of the microorganisms can obtain energy from consuming the C—OH groups, which also has a cumulative effect on aromatic carbon, and increasing the complexity degree of SOC molecules. Influenced by the NH⁺⁴N that served as the main N form, the microorganisms are more inclined to consume much more carboxyl functional groups of SOC and make them decomposed and transformed into much more alcoholic hydroxyl groups (C—OH). There are some main types of SOC functional groups existing in the albic soil with corn straw, such as aromatic hydrocarbon C〖CDS1〗C and C—H, aliphatic hydrocarbon, carboxyl group C---O, alcoholic hydroxyl group C—OH and graphite type C---C.

Key words: nearedge Xray absorption fine structure (NEXAFS) spectrum, organic carbon functional group, albic soil, corn straw, quantitative analysis, nitrogen form