The 19-years inorganic fertilization increased bacterial diversity and altered bacterial community composition and potential functions in a paddy soil

Abstract

Although the consequences of long-term inorganic fertilizer application on microbial communities have been widely investigated, the potential links between soil properties, microbial communities, and functions remain unclear in reddish paddy soil in southern China. Herein, we used Illumina Miseq sequencing technology to evaluate bacterial communities after extensive application of fertilizers started in 1998. The five treatments were control (unfertilized), N1P1K (low N plus low P plus normal potassium (K)), N2P1K (high N plus low P plus normal K), N1P2K (low N plus high P plus normal K), and N2P2K (high N plus high P plus normal K). High amounts of inorganic fertilization increased bacterial biodiversity whereas various fertilization treatments did not present any significant difference. All fertilized treatments exhibited Proteobacteria, Acidobacteria, Chloroflexi, and Actinobacteria as the main phylum. The remaining four fertilizer treatments resulted in an increase in the relative abundances of Proteobacteria, Bacteroidetes, as well as Gemmatimonadetes compared to the control, whereas a reduction in Acidobacteria, Chloroflexi, Nitrospirae, as well as Planctomycetes was observed. The principal coordinate analysis showed that bacterial communities in the control, N1P1K, and N2P1K treatments differed from that of the N1P2K and N2P2K treatments. Bacterial biodiversity and community composition were largely affected soil N:P ratios and available phosphorus. Functional groups of anoxygenic photoautotrophy S oxidizing, anoxygenic photoautotrophy, photoautotrophy, photoautotrophy, photoheterotrophy, phototrophy, nitrate denitrification, nitrite denitrification, nitrous oxide denitrification, denitrification, nitrite respiration, nitrate respiration, nitrate reduction, nitrogen respiration, and sulfur respiration were enhanced by long-term inorganic fertilization, while functional groups of aerobic nitrite oxidation, nitrogen fixation, sulfate respiration, dark sulfide oxidation, dark oxidation of sulfur compounds, and cellulolysis were decreased. Taken together, we concluded that bacterial communities in a reddish paddy soil would be phylogenetically and functionally shifted by long-term inorganic fertilization.