试验采集不同种植年限设施菜地土壤样品,测定土壤有机质(SOM)、可溶性有机碳(DOC)、胡敏酸(HA)、富里酸(FA)、微生物量碳(MBC)、微生物商(C_(mic)-to-C_(org))、C矿化和E4/E6值等指标,结合傅立叶变换红外光谱技术解析不同种植年限土壤有机质组成与结构变化的规律。结果显示,随着种植年限的增加,SOM、DOC、HA、HA/FA、MBC、C_(mic)-to-C_(org)、E4/E6值、C矿化率和CO_2释放速率均出现明显下降趋势,其中MBC、C_(mic)-to-C_(org)、C矿化率、CO_2释放速率和HA/FA在种植6 a时下降最明显,之后变化缓慢。与露天农田土壤(CK)相比,设施菜地呈现较高的SOM、DOC、Humus、HA、FA、HA/FA和E4/E6。胡敏酸红外光谱图谱显示设施菜地种植20 a处理土壤芳构化程度高,结构稳定,难以降解,其他三种种植年限(3 a、6 a和10 a)的芳构化程度相对较低,脂肪族成分相对较高。综上可知,设施菜地土壤有机质组成与结构随着种植年限的增加具有规律性变化,结果加深了对设施菜地土壤有机质演变规律的认知。
In this study, we collected soils in greenhouse vegetable with different culnvated years to explore meinfluences on the composition and structure of soil organic matter. Soil organic carbon (SOC), dissolved organic carbon(DOC), humic acid (HA), fulvic acid (FA), microbial biomass carbon (MBC), the ratio of MBC to SOC (Cc-to-C), Cmineralization rate and E4/E6 were measured and Fourier transform infrared spectrometer (FTIR) technique was usedto analyze the variation tendency of the composition and structure of soil organic matter with different cultivated years.Our results demonstrated that SOC, DOC, HA, HA/FA, MBC, C-c-to-C- E4/E6, CO2-C release rate and Cmineralization rate showed obviously decreased, especially in cultivation for 6 years. The result of F-FIR analysisindicated that cultivation for 20 years showed the highest aromaticity of HA, with less aliphatic and more complexmolecular structure. In summary, the composition and structure of soil organic matter in greenhouse vegetable showedcertain variation tendency with cultivated years.