Response of microbial communities and enzyme activities to amendments in saline-alkaline soils

Abstract Soil salinization is one of the key factors that threatens plant existence worldwide and is a major challenge to sustain crop production and soil quality. However, there has been limited research on the responses of microbial communities and enzyme activities under soil amendments application in saline alkaline soils. Here, we explored the response of microbial communities and enzyme activities to soil amendments based on 7-year field experiment. The five treatments included FA, amended with farm manure; DE, amended with desulfurization gypsum; SA, amended with sandy soil; M, amended with a mixture of FA, DE and SA; and CK, non-amended control. Relative to the CK treatment, the four amendments, particularly FA, DE and M, significantly decreased the soil pH. Enzyme activities (catalase, urease, alkaline phosphatase and cellulase) were increased in the FA, DE and M treatments, while no difference was observed between SA and CK, except in cellulase. A total of 439,575 effective sequences after filtering out of 1,017,148 raw reads were obtained resulting in 9096 OTUs. Six bacterial phyla of the highest relative abundance were detected including Proteobacteria , Chloroflexi , Bacteroidetes , Actinobacteria , Acidobacteria and Firmicutes across all soil samples (accounting for >85% of the reads). The bacterial community richness was increased in the FA, DE and M treatments, whereas it showed a similar pattern between the CK and SA treatments. Bacterial community diversity was remarkably higher in the M, FA and DE treatments compared to that of CK, while it was reduced in SA. There was a higher similarity in the bacterial communities among DE, FA and M, as well as between CK and SA. Our findings showed that organic manure is a better application approach for the restoration of saline-alkaline soil based on improving the bacterial community and enzyme activities.