玉米秸秆还田对土壤微生物群落组成的影响

Effects of maize straw returning on soil microbial community composition

为揭示土壤微生物群落对持续玉米秸秆还田的响应机制,采用单因素随机区组设计,以秸秆不还田(T0)为对照,设3000 kg/hm^(2)(T1)、6000 kg/hm^(2)(T2)、9000 kg/hm^(2)(T3)、12000 kg/hm^(2)(T4)4个秸秆还田量。采用磷脂脂肪酸(PLFAs)指纹图谱的方法,研究了连续6年玉米秸秆还田管理后土壤微生物群落组成的季节性变化特征,分析了土壤基本理化及生物学性状与土壤微生物群落组成、玉米产量间的关系。结果表明:持续秸秆还田后,土壤中全氮、总碳、碱解氮含量和土壤呼吸强度增加,土壤pH值降低。持续秸秆还田能增加土壤微生物群落的PLFAs含量;玉米大喇叭口期对应土壤细菌、革兰氏阳性菌(G+)、革兰氏阴性菌(G^(-))的PLFAs含量在T0与T1间有显著差异(P<0.05),但不同秸秆还田量间无显著差异(P>0.05);T3、T4处理在玉米成熟期对应土壤细菌、G^(+)、G^(-)、真菌、放线菌的PLFAs含量与T0间有显著差异(P<0.05);不同秸秆还田量下的土壤革兰氏阳性菌/革兰氏阴性菌(G+/G^(-))比值无显著变化(P>0.05),但9000 kg/hm^(2)(T3)和12000 kg/hm^(2)(T4)的秸秆还田量显著提高了土壤真菌/细菌(F/B)的比值。Pearson相关分析表明,土壤全氮、总碳、碱解氮、速效钾、pH值及土壤呼吸强度是影响土壤微生物群落组成及玉米产量的主要因素。持续玉米秸秆还田后,以PLFAs表征的土壤微生物群落具有明显的季节性变化特征;土壤全氮、总碳是驱动土壤微生物群落生物量变化的主要因素,连续不同玉米秸秆量还田未对玉米产量产生影响。

To reveal the effect of continuous maize straw returuing to the soil microbial community,five treatments were designed according to the method of single factor randomized block design,and no straw returning to the field(T0)was selected as the control,with the straw returning amount of 3000 kg/hm^(-2)(T1),6000 kg/hm^(-2)(T2),9000 kg/hm^(-2)(T3)and 12000 kg/hm^(-2)(T4).The seasonal variation of soil microbial community composition was studied by using phospholipid fatty acids(PLFAs)fingerprints after maize straw returning to the field for six year,and the relationship among soil basic physicochemical and biological properties,soil microbial community composition,and maize yield were discussed.The results showed that the contents of total nitrogen,total carbon,available nitrogen and soil respiration intensity were increased and soil pH decreased after straw returning to the fields.Continuous straw returning can increase the PLFAs contents of soil microbial community.The PLFAs of soil bacteria,gram-positive bacteria(G^(+))and gram-negative bacteria(G^(-))at the trumpet stage showed significant difference between T0 and T1(P<0.05),but there was no significant difference between different straw returning to the fields(P>0.05).Compared with control(T0),the PLFAs contents of soil bacteria,G^(+),G^(-),fungi and actinomycetes at the maize mature stage of T3 and T4 treatment had significantly difference(P<0.05).There was no significant change of the gram-positive/gram-negative(G^(+)/G^(-))under different treatment of straw returning(P>0.05),but the ratio of soil fungi/bacteria(F/B)were significantly increased under the treatment of 9,000 kg·hm^(-2)(T3)and 12,000 kg·hm^(-2)(T4)straw returning to the fields.Pearson correlation analysis showed that soil total nitrogen,total carbon,available nitrogen,available potassium,pH and soil respiration intensity were the main affecting factors to soil microbial community composition and maize yields.We concluded that the soil microbial community marked by PLFAs showed an obvious seasonal trend after maize straw returning to the fields.Soil total nitrogen and total carbon were the main factors to drive the change of soil microbial community biomass marked by PLFAs.There is no significant difference of the maize yields after the different amounts of straw returning on soil.