Bacterial diversity in different soil depths in pear orchard

【Objective】 By studying the changes of bacterial microbial communities in different soil depths in pear orchards, it was hoped to provide references for precise fertilization and soil microbial community structure improvement in pear orchards.【Method】 Taking the pear orchard soil in Kongzhuang Experimental Base of Changli Institute of Pomology, Hebei Academy of Agriculture and Forestry Sciences as the research object, the physical and chemical properties and bacterial microbial communities of different soil depths(5-15 cm, 15-25 cm and 25-35 cm) were measured. Revealing trends in soil physicochemical properties and bacteria at different soil depths and the relationship between them.【Result】 With the continuous increase of soil depth, the content of soil organic matter, available nitrogen, available phosphorus. There were 3025 identical OTUs in different soil depths, with a consistency of 60.00%. Shannon index, Simpson index, Chao1 index, ACE index all gradually decreased with the increase of soil depth, and there was no significant difference between the treatments of each index(P>0.05). Principal component(PCoA) analysis found that the 5-15 cm and 15-25 cm soil depths were similar in bacterial community structure, and the 25-35 cm and 5-15 cm and 15-25 cm soil depths were quite different in community structure. The phylum of soil bacteria was mainly Proteobacteria and Acidobacteriota; the bacterial genus was mainly RB41, Candidatus Solibacter, Bryobacter;Escherichia coli relative abundance was the highest at bacterial species level. Organic matter, available nitrogen, available phosphorus and available potassium all had extremely significant positive correlation with the Proteobacteria(P<0.01), and had significant negative correlation with the Crenarchaeota(P<0.05, the same below). Organic matter, available nitrogen and available phosphorus all had significant positive correlation with Shannon index.【Conclusion】 Soil depth has great impact on soil physical and chemical properties and bacterial community structure, and bacterial communities have strong correlation with soil physical and chemical factors. The distribution of bacterial communities at different soil depths of pear orchard can be used as a basis for improving bacterial community diversity.