长期施肥对旱作区农田土壤细菌群落组成和多样性的影响

Effects of long-term fertilization on soil bacterial community composition and diversity in dry farming region

为阐明长期有机、无机施肥对旱作区土壤细菌群落组成及多样性的影响机制,以农田土壤生态系统为研究对象,采用单因素随机区组设计,利用长期定位试验(11年)和高通量测序的方法,研究了不施肥(对照,T0)、单施化肥(T1)、化肥配施羊粪有机肥(T2)和化肥配施生物有机肥(T3)对土壤的影响,分析了处理间土壤细菌群落组成及多样性的差异,探究了驱动土壤细菌群落组成及多样性变化的主要土壤环境因子。结果表明:与T0相比,羊粪有机肥、生物有机肥与化肥配施能显著提高土壤全氮、全磷、有机质、碱解氮、有效磷和铵态氮的含量,其中T2处理效果最显著(P<0.05)。各施肥处理下土壤放线菌门(Actinobacteria)、变形菌门(Proteobacteria)、绿弯菌门(Chloroflexi)细菌为优势菌门;羊粪有机肥、生物有机肥与化肥配施处理降低了土壤放线菌门的相对丰度,增加了绿弯菌门、拟杆菌门和厚壁菌门的相对丰度,T2处理与T0处理间有显著差异(P<0.05)。与T1处理相比,羊粪有机肥、生物有机肥与化肥配合施用使土壤硝化螺旋菌门的相对丰度显著降低。类诺卡氏菌属(Nocardioides)、KD4-96和Subgroup_6为土壤细菌群落的优势菌属。T2处理较T3处理更显著地降低了土壤类诺卡氏菌属(41.15%)、芽球菌属(41.67%)和红杆菌属(27.45%)的相对丰度。与T0处理相比,T2处理更显著增加了细菌群落物种数、群落辛普森指数、香农指数和Chao1指数(P<0.05)。冗余分析表明,土壤有机质(P=0.001)、pH(P=0.003)是驱动土壤细菌群落组成及多样性变化的主要因素。土壤pH以及有机质含量高低对驱动旱作区土壤细菌群落组成以及土壤细菌多样性变化均产生直接效应。因此,化肥与羊粪有机肥相结合的长期施肥管理是优化旱作区区域农田养分管理、提升土壤肥力的有效途径。

In order to elucidate the effects of long-term organic and inorganic fertilization on soil bacterial community composition and diversity in dry farming region,farmland ecosystem was used as the research object,the single factor randomized block design was adopted,long-term(11 years)fixed fertilization experiment was carried out and high-throughput sequencing method were used.Four treatments of no fertilizer(T0),only chemical fertilizers(T1),chemical fertilizers with sheep manure(T2)and chemical fertilizers with biological organic fertilizer(T3)were selected.The differences between the soil bacterial community composition and diversity were analyzed,and their environmental driving factors were investigated.The results showed,the treatments of organic fertilizers with inorganic fertilizers significantly increased the contents of soil total nitrogen,total phosphorus,organic matter,alkali-hydrolyzable nitrogen,available phosphorus and ammonium nitrogen.The T2 had the most obviously differences(P<0.05),compared with T0.Actinobacteria,Proteobacteria and Chloroflexi were the dominant phylum of soil bacteria among all treatments.Compared with T0,the treatments of organic with inorganic fertilizers decreased the relative abundance of soil Actinobacteria,but increased the relative abundance of Chloroflexi,Bacteroidetes and Firmicutes,and there was significant difference between T2 and T0(P<0.05).Compared with T1,long-term application of organic fertilizer with different dosage and source combined with chemical fertilizer significantly reduced the relative abundance of Nitrospirae in soil.Nocardioides,KD4-96 and Subgroup_6 were the dominant genus in the long-term experiment.The relative abundance of Nocardioides(41.15%),Blastococcus(41.67%)and Solirubrobacter(27.45%)in soil were significantly decreased in T2 compared with T3.Compared with T0,T2 significantly increased the number of bacterial species,Simpson index,Shannon index and Chao1 index of bacterial community(P<0.05).Redundancy analysis(RDA)analysis showed that soil organic matter(P=0.001)and pH(P=0.003)were the main driving factors to the changes of soil bacterial community structure and diversity.Soil pH and organic matter had a direct effect on the change of soil bacterial community composition and diversity.Long-term combined application of chemical fertilizer and sheep manure fertilization had the most significant effects on soil fertility and soil bacterial community structure and diversity.Therefore,the long-term fertilization management of chemical fertilizer combined with sheep manure is an effective way to improve nutrient management and maintain soil fertility in dry farming region.