不同轮作和秸秆还田方式对黑土细菌群落结构的影响

Effects of Different Crop Rotation and Straw Returning Methods on Bacterial Community Structure in Black Soil

轮作和秸秆还田是黑土地保护与利用的有效措施,微生物作为土壤养分循环的驱动者,其群落结构和多样性是衡量农田生态系统稳定性的重要指标之一。采用高通量测序技术明确不同玉米-大豆轮作和秸秆还田方式下0~20 cm耕层土壤细菌群落结构及组成差异。结果表明:与玉米连作相比,玉米-大豆轮作显著提高了土壤细菌群落的多样性。Rhizobiaceae作为根瘤菌的代表科,在轮作处理相对丰度显著高于玉米连作处理,且与土壤碱解氮含量呈显著负相关性。功能基因预测分析表明,轮作处理的氧化亚氮还原酶基因和固氮酶nifB基因的相对丰度均显著高于玉米连作处理,而固氮酶nifH基因的相对丰度显著低于连作处理,表明轮作改变了土壤中与氮周转相关微生物的丰度。在不同秸秆还田方式处理中,玉米秸秆旋耕还田处理土壤养分含量最高,土壤细菌群落结构主要受速效钾、总氮和有机质含量的影响。Streptomycetaceae和Burkholderiaceae相对丰度在秸秆旋耕还田中显著高于秸秆深翻还田和覆盖还田,且与土壤有机质和全氮含量呈显著正相关。结合土壤养分和土壤细菌群落结构研究结果,玉米-大豆2∶1轮作下玉米秸秆旋耕还田对耕层土壤培肥效果最好。

Crop rotation and straw returning are effective measures for the conservation use of black land.Soil microorganisms are considered as the driver of soil nutrient cycling,and their community structure and diversity are one of the important indicators for agro-ecosystem stability.In this study,high-throughput sequencing was used to clarify the differences in soil bacterial community structure in the 0-20 cm under different maize-soybean crop rotation and straw returning systems.The results showed that maize-soybean rotation system significantly increased soil bacterial diversity,compared with maize continuous cropping.And available potassium,available phosphorus and total nitrogen were significantly correlated with bacterial community structure.The relative abundance of Rhizobiaceae,which was a representative family of legume bacteria,was significantly increased in rotation system,and it had significantly negative correlation with available nitrogen.The results of PICRUST showed that the relative abundance of nitrous oxide reductase gene and nitrogenase nifB gene in rotation system was higher than that in continuous cropping,while the relative abundance of nitrogenase nifH gene was lower than that in continuous cropping.The results suggested that maize-soybean rotation system had changed the abundance of microorganisms related to nitrogen turnover in soil.In different straw returning method treatments,soil nutrient was the highest in maize-soybean 2∶1 with maize straw returning by rotary tillage.The available potassium,total nitrogen and soil organic matter were significantly correlated with bacterial community structure.The relative abundance of Streptomycetaceae and Burkholderiaceae in rotary tillage with straw returning was significantly higher than that in moldboard-returning and cover-returning treatment,and it had significantly positive correlation with soil organic matter and total nitrogen.