Effects of Salinity Accumulation on Physical, Chemical, and Microbial Properties of Soil under Rural Domestic Sewage Irrigation

Under irrigation with saline wastewater, SO42−, Cl−, and Ca2+ aggregated in the topsoil, and Mg2+ was significantly higher in the deeper soil than in the topsoil and 40 cm soil layers. The abundance of Zoopagomycota, Ascomycota, Mortierellomycota, Basidiomycota, Chytridiomycota, Rozellomycota, Blastocladiomycota, Monoblepharomycota, Mucoromycota and Olpidiomycota in the surface soil was influenced by Mg2+, whereas Ca2+ affected the abundance of Zoopagomycota and Chytridiomycota. In the 40 cm soil layer, Mg2+ and Cl− promoted Actinobacteria, Proteobacteria, Nitrospirae, Firmicutes, Entotheonellaeota, Myxococcota, Gemmatimonadota and Methylomirabilota, whereas they inhibited Planctomycetota, Acidobacteria, Chloroflexi, Patescibacteria and Bacteroidota. In the 80 cm soil layer, SO42− and Cl− promoted Rozellomycota, Mortierellomycota, Chytridiomycota, Ascomycota, and Mucoromycota, but had a negative effect on Glomeromycota, Blastocladiomycota, Olpidiomycota and Monoblepharomycota. The increase in salinity significantly reduced the abundance of the Actinomycetes phylum and the Amoebozoa phylum. Both saprophytic and symbiotic fungi decreased with increasing salinity.