玉米秸秆不同还田方式对黑土有机碳组成和结构特征的影响

为研究玉米秸秆不同还田方式对黑土有机碳组成和结构特征的影响,以吉林农业大学微区试验田黑土为研究对象,设置CK(未施用秸秆)、C1(秸秆浅施)和C2(秸秆深还)共3种处理,通过腐殖质组成修改法提取富里酸(Fulvic acid,FA)、胡敏酸(Humic acid,HA)和胡敏素(Humin,HM),IHSS方法提取HA样品,并测定其元素组成、红外光谱和差热性质等结构性质。结果表明:秸秆还田有利于土壤和各腐殖质组分有机碳含量提高,土壤腐殖质PQ值(HA在可提取腐殖质中所占的比例)显著增加;与CK相比,C1处理表层(0~20 cm)的SOC、HA、FA和HM有机碳含量明显增加,分别增加了21.8%、27.3%、11.5%和30%;C2处理亚表层(20~40cm)的SOC、HA、FA和HM有机碳含量显著增加,分别增加了26.3%、32%、13.4%和31.9%。C1和C2处理均使HA的氧化度、缩合度和热稳定性降低,脂族链烃和芳香碳含量增加,结构趋于简单化。这些变化在C1处理中主要体现在表层,与CK相比,C1处理表层HA的(O+S)/C比值降低了11.3%,I2920/I1620的比值增加了23.4%;C2处理主要为亚表层HA结构的变化,与CK相比,C2处理亚表层HA的(O+S)/C比值降低了9.1%,I2920/I1620的比值增加了23%。这一研究结果对阐明土壤培肥机理和指导秸秆还田实践有重要意义。

Effect of different ways of corn stover application to soil on composition and structural characteristics of organic carbon in black soil

The practice of corn stover application to soil is an important measure to improve soil fertility and increases soil organic matter. However, the influence of different ways of corn stover application on humus composition and humic acid structural characteristics in soil is not well understood. The black soil of micro area corn field at the Jilin Agricultural University was taken as the research object, and three treatments were set as follows:CK(No corn stover incorporated), C1(corn stover incorporated to shallow layer), C2(corn stover deep incorporation). Fulvic acid(FA), humic acid(HA) and humin(HM) were extracted by the modified humus component method, and purified HA was prepared by IHSS method, and to measure its structural properties of element composition, infrared spectroscopy and differential thermal property. As the results show:Corn stover application to soil improved the organic carbon contents of soil humic components significantly, PQ values of soil humus(the radio of HA proportion in ex-tractable humus) increased significantly. compared with CK, the C1 treatment of SOC, HA, FA and HM in the surface soil(0~20 cm) significantly increased by 21.8%, 27.3%, 11.5% and 30% respectively, The C2 treatment of SOC, HA, FA and HM in the subsurface soil(20~40 cm) significantly increased by 26.3%, 32%, 13.4% and 31.9% respectively. It was found that C1 and C2 treatments could reduce the condensation degree, oxidation degree and thermal stability of HAs, increase the content of aromatic-C and aliphatic chain hydrocarbon, and make HA simpler in structure. These changes were representative in surface soil for the HA of C1 treatment, compared with CK, the (O+S)/C ratio decreased by 11.3%, the aliphatic-C/aromatic-C ratio(2920/1620) increased obviously by 23.4%. On the other hand, for the HA of C2 treatment, above changes mainly appeared in subsurface soil, the(O+S)/C ratio was 9.1% lower than CK, the aliphatic-C/aromatic-C ratio(2920/1620) significantly increased by 23% compared with CK. It has great significance to clarify the mechanism of improving soil fertility and to guide the practice of corn stover application to soil.