Abstract: Changes on the bacterial community in soil at tea plantations in northwestChina upon the reduced application of chemical fertilizers were studied. Plotsat a tea plantation were treated using no fertilizer (CK), conventional chemicalfertilization (CF), 50.7% replacement on chemical fertilizers with an organicfertilizer (OF), 34.4% replacement on chemical fertilizers with slow releasefertilizers (SRF) or 30.3% replacement on chemical fertilizers with a biochar-basedformulation fertilizer (BF). Three years after the treatments, in November 2019,surface soils in the depth of 0-20cm at the lots were sampled. The method of high-throughputsequencing on the V3-V4 16S rRNA gene region was employed to determine the compositionand diversity of bacterial community in the specimens. Key elements affectingthe community changes in the plantation soil were analyzed. The Sobs, Shannon,Simpson, ACE, and Chao1 indices on the soils ranged from 1,939 to 2,219, 6.09to 6.52, 0.0053 to 0.0062, 2,625.66 to 2,962.15, and 2,562.32 to 2,948.01,respectively. Among the treatments, OF rendered a significantly greaterbacterial diversity than CF (P<0.05). In all soil samples, abundant specieswere isolated encompassing 32 phyla, 80 classes, 202 orders, 352 families, and667 genera. The dominant phyla were Proteobacteria, Actinobacteria,Chloroflexi, Acidobacteria, and Firmicutes (relative abundance >10%), which accountedfor 89.44-91.69% of the total reads in different specimens. Compared to CK, CFsignificantly increased the relative abundance on Chloroflexi andKtedonobacteria (P< 0.05), while SRF significantly decreased that onKtedonobacteria (P < 0.05). No significant differences among the differenttreatments on other phyla and classes were observed. The redundancy analysis(RDA) indicated that available phosphorus, alkali-hydrolyzable nitrogen, andavailable calcium were the major factors affecting the abundance and diversityof the bacteria community in the soil. On the other hand, since thefirst two environmental indices could explain only 28.26% and 32.99% for theobserved variations, soil properties per se could not satisfactorily related tothe changes in the bacterial communities. Further study would be necessary tounveil the complex relationship.