不同年限烤烟连作对土壤养分和微生物变化的影响

为探究烤烟连作障碍的关键影响因素及规律，对汉中地区种植5种不同年份处理：连作0 a（CK）、连作2 a（T1）、连作4 a（T2）、连作6 a（T3）和连作8 a（T4）的烤烟土壤进行了土壤理化性质、微生物多样性及群落结构变化的分析。结果显示：烤烟土壤有机质、土壤pH和总碳含量随着种植年限的增加而降低；T4处理相比于CK处理，土壤有机质、土壤pH和总碳含量分别减少8.34%、25.39%和25.20%；土壤中细菌和真菌多样性及丰富度均呈现先增加后减少的趋势，其中细菌优势菌门为放线菌门、变形菌门、酸杆菌门、绿弯菌门和厚壁菌门；真菌优势菌门为子囊菌门、担子菌门和毛霉菌门，相比于CK处理，T3处理下微生物相对丰度变化较大，其中放线菌门、厚壁菌门和担子菌门变化幅度分别为4.04%、6.24%和28.86%。结果表明，连作降低了土壤有机质含量、土壤pH和全碳含量，影响土壤微生物群落组成。

Effects of different years of continuously cropping flue-cured tobacco on changes of nutrients and microbial community in soil

The changes in the physicochemical properties， the diversity of microorganisms and the structure of microbial community in the soil planted continuously with flue-cured tobaccos of different planting years including continuous cropping for 0 year （CK）， continuous cropping for 2 years （T1）， continuous cropping for 4 years （T2）， continuous cropping for 6 years （T3）， and continuous cropping for 8 years （T4） in Hanzhong area of Shaanxi Province were analyzed to study the key factors affecting the obstacles for continuous cropping of flue-cured tobacco and its patterns. The results showed that the organic matter， pH， and the content of total carbon in soil decreased with the increasing years of planting. The organic matter， pH， and the content of total carbon in the soil of T4 was 8.34%， 25.39%， and 25.20% lower than that of CK. The diversity and abundance of bacteria and fungi in soil showed a trend of increasing first and then decreasing， with the dominant bacterial phyla being Actinobacteriota， Proteobacteria， Acidobacteriota， Chloroflexi and Firmicutes. The dominant fungal phyla were Ascomycota， Basidiomycota， and Mucoromycota. Compared with CK， the relative abundance of microorganisms under T3 changed significantly， with change in Actinobacteria， Firmicutes， and Basidiomycota of 4.04%， 6.24%， and 28.86%， respectively. It is indicated that continuous cropping of flue-cured tobaccos reduces the content of organic matter， pH， and the content of total carbon in soil， affecting the composition of microbial community in soil.