Effect of 35 years inorganic fertilizer and manure amendment on structure of bacterial and archaeal communities in black soil of northeast China

Abstract

Black soil is common in northeast China and plays an important role in Chinese crop production. However, in the past three decades, inappropriate use of fertilizer has caused a sequence of agroecological issues. The objective of this research was to evaluate the effect of long-term fertilizer on the microbial communities in black soil. The soil was subjected to four fertilization regimes: without fertilizer (CK); manure (M); nitrogen, phosphorus and potassium inorganic fertilizer (NPK); and inorganic fertilizers with manure (MNPK). The soil pH was decreased by inorganic fertilizers and increased by manure. Quantitative PCR analysis of microbial community size and Illumina platform-based analysis of the V4 16S rRNA gene region were performed to characterize soil microbial abundance and to compare community structure and diversity. Microbial community size was enhanced by the incorporation of inorganic fertilizer and manure. Microbial diversity was decreased by inorganic fertilizer and increased by the incorporation of inorganic fertilizer and manure. The predominate phyla in all samples were Proteobacteria (29.39–33.48%), Acidobacteria (13.14–16.25%) and Actinobacteria (9.32–10.77%). The relative abundance of different classes significantly differed among the different treatments, especially MNPK and NPK. Acidobacteria and Deltaproteobacteria were relatively stable in organic fertilizer treated soil. Gammaproteobacteria, Alphaproteobacteria and Betaproteobacteria were sensitive to all the fertilization regimes. Comparatively, Spartobacteria was stable in response to fertilization practices. Principal coordinate analysis indicated that microbial communities were primarily clustered into three groups: CK and M were clustered together; MNPK was improved by manure and separated from NPK. Shannon and Simpson indexes were significantly correlated with soil pH and the concentrations of available phosphorus and total phosphorus. Redundancy analysis indicates that microbial communities were closely positively correlated with soil nitrate nitrogen concentration (P=0.002) and pH (P=0.002). These results indicate that inorganic fertilizer plus manure increased microbial size and diversity and changed microbial composition.