Effects of different planting patterns on soil fertility and soil bacterial community structure in mulberry field

【Objective】To reveal relationship between soil fertility,soil microbial structure and diversity,so as to provide reference for intercropping pattern and fertilization management in mulberry field.【Method】Mulberry monoculture group was taken as control(CK),and 3 intercropping patterns,mulberry-soybean intercropping(MSS),mulberry-peanut intercropping(MPP),mulberry-sweetpotato intercropping(MST)to conduct a 2-year field experiment. Soil physical and chemical property,bacterial diversity index and community structure characteristics under these 4 patterns were analyzed.【Result】Soil nutrient content,OTU number,α diversity index and soil bacterial community structure were different under various planting patterns. Compared with CK,intercropping significantly changed soil pH,available potassium content and increased content of soil organic matter,total phosphorus and available phosphorus. α diversity analysis showed that bacterial OTU number,ACE index,Chao1 and Simpson indexes in soil of mulberry field were higher than those in CK. ACE index of intercropping was significantly different from that in CK(P<0.05). llumina HiSeq highthroughput sequencing results showed that planting patterns influenced the dominant bacterial phyla accounting for more than 1%. Proteobacteria,Actinobacteria,Bacteroidetes,Gemmatimonadetes and Nitrospirae were dominant groups in intercropping soil among the top 10 phyla with the highest abundance,with a total of relative abundance of 62.32%-71.27%.At the genus level,Sphingomonas,Uncultured_Bacterium_f_SC-I-84,Uncultured_bacterium_f_Chitinophagaceae,Ilumatobacter,Nitrospira,JGI_0001001-H03,Ramlibacter and Flavisolibacter were the dominant bacterial genera in intercropping soil,which were 60.9%,50.0%,19.1%,17.9%,11.3%,25.0%,50.5% and 45.6% compared with CK,respectively. In addition,there was certain correlation between soil bacterial genera comunity relative abundance and soil nutrient content. 【Conclusion】Planting patterns significantly change soil pH,alkali-hydrolyzable nitrogen and available potassium content,and influence composition of soil dominant bacterial classification level(phylum and genus)and relative abundance in mulberry field soil,thus altering bacterial community structure and species richness. Soybean-peanut intercropping is beneficial to improve soil physical and chemical properties in mulberry field,soil bacterial diversity,and maintaining mulberry field soil fertility.