Liming shifts the chemical properties and microbial community structures of peanut soils with different initial pH values

Peanut (Arachis hypogaea) yield is often reduced by calcium (Ca) deficiency. Ca deficiency of peanut plants is likely to occur in most acidified soils (ASs, pH < 5.5) and some neutral soils (NSs, pH 6.5–7.5) in China. Liming is widely used to supply Ca and increase peanut yield. Nevertheless, the effects of liming on the chemical and microbial properties of peanut soils are still unclear, particularly in soils with different initial pH values. A pot experiment was conducted to investigate the effects of CaO (with application rates of 0, 225 and 450 kg/ha) on the chemical properties and bacterial communities and network structures in AS and NS. Compared with CK (CaO 0), the addition of lime improved the pH as well as the exchangeable calcium (ECa) and total nitrogen (TN) contents of both soils. The peanut yield as well as the available nitrogen (AN), available phosphorus (AP) and exchangeable potassium (EK) contents were also higher in AS treated with lime than in that treated with no lime, while lime application to NS had little effect on the yield and AN and EK contents and even significantly reduced the AP content. Lime amendment, especially for the high lime treatment, significantly increased the α-diversity indexes of AS, while no difference in α-diversity was observed among treatments with different liming rates in NS. A weaker β-diversity response to lime addition was observed in NS than in AS. Lime application strongly altered the bacterial community structure of AS by increasing the relative abundances of copiotrophic taxa (e.g., Saccharibacteria) involved in C and N metabolism and pathogen resistance while reducing the percentages of oligotrophic taxa (e.g., Chloroflexi), which were also related to C and N metabolism. In NS, liming favored the growth of Verrucomicrobia with the potential function of denitrification, while microbial groups related to nitrification (e.g., Nitrospirae) and nitrogen fixation (e.g., Acidobacteria) were weakened under liming treatments. Additionally, network analysis revealed that lime amendment provided a more complex and stable network for AS than for NS. Taken together, the responses of the peanut yield, soil chemical properties, bacterial α-diversity and community composition to lime were stronger and more positive in AS than in NS. Results from this study provide critical data for understanding the influence of liming on soil habitats in main peanut-planting areas in China.