玉米秸秆对土壤有机质含量及微生物群落结构的影响

【摘要】为秸秆还田改善土壤生态功能提供理论依据,以添加秸秆后不同有机质含量变化的土壤为研究对象,利用磷脂脂肪酸（PLFA）法测定土壤微生物群落结构的分布,分析土壤微生物结构与有机质含量变化的关系。结果表明:玉米秸秆添加后引起土壤有机质呈大幅正向增加（I 1 ）、小幅度正向增加（I2）和负向变化（I 3 ）3种趋势,其中小幅度正向增加的I2磷脂脂肪酸的种类和绝对含量均低于I 1 和I 3 ,而直链单不饱和脂肪酸/环丙烷脂肪酸（A/B）、直链饱和脂肪酸/直链单不饱和脂肪酸（C/A）、支链异构饱和脂肪酸/支链反异构饱和脂肪酸（iso/anteiso）值均高于I 1 和I 3 ;有机质大幅正向增加的I 1 磷脂脂肪酸的种类和绝对含量为3组中最高,且玉米秸秆处理过程中刺激16:0、18:1w6c、18:1w9c、16:0 10-methyl和19:0cyclo w8c所表征的优势类群的增殖,特征性菌群细菌/真菌和革兰氏阳性菌/革兰氏阴性菌（G+/G—）比值较I 1 和I2低;有机质负向变化的I 3 土壤中表征优势类群的磷脂脂肪酸的绝对含量均低于I 1 ,且支链饱和脂肪酸绝对含量为3组土壤中最高;主成分分析表明,I 1 和I 3 土壤微生物种类间无明显差别。土壤初始有机质含量高,玉米秸秆添加后土壤有机质变化幅度大,土壤微生物种类及丰度高。

【英文摘要】The correlation between soil microbial structure and organic matter variation after adding cornstalk was analyzed by PLFA method to provide the theoretical basis for biological function of straw turnover to improve soil.Results：Three groups of substantial positive increase（I1）,small scale positive increase（I2）and negative change（I3）are divided into according to variation of soil organic matter content after adding cornstalk.The PLFA kind and absolute content of I2 both lower than I1 and I3but the ratio values of straight chain monounsaturated fatty acid/cyclopropane fatty acid,straight chain saturated fatty acid/straight chain monounsaturated fatty acid and branched isomerism saturated fatty acid（iso）/branched trans-isomerism saturated fatty acid（anteiso）are higher than I1 and I3.The PLFA kind and absolute content of I1 is the highest among three groups,which can stimulate multiplication of dominant species represented by16：0,18：1w6c,18：1w9c,16：0 10-methyl and 19：0cyclo w8 cduring cornstalk treatment process.The ratio values of bacteria/fungi and G＋/G-is lower than I1 and I2.The absolute PLFA content of representation dominant species in I3 soil is lower than I1 but its branched saturated fatty acid absolute content is the highest among three groups.The principal component analysis indicates there is no obvious difference in soil microbial species between I1 and I3.The variation range of soil organic matter content is significant and the soil microbial species and abundance increase after adding cornstalk into the soil with higher organic matter content.