Soil microbial activity and community structure as affected by exposure to chloride and chloride-sulfate salts

Abstract

Mixed or chloride salty ions dominate in saline soils, and exert wide-ranging adversely affect on soil biological processes and soil functions. The objectives of this study were to (1) explore the impacts of mixed (0, 3, 6, 10, 20 and 40 g Cl-/SO 4 2-salt/kg dry soil) and chloride (0, 1.5, 3, 5, 8 and 15 g Clsalt/kg dry soil) salts on soil enzyme activities, soil physiological functional (Biolog) profiles and microbial community structure by using soil enzymatic, Biolog-Eco microplates as well as denaturing gradient gel electrophoresis (DEEG) methods, and (2) determine the threshold concentration of soil electronic conductivity (EC 1:5) on maintaining the functional and structural diversity of soil microbial community. The addition of either Clor mixed Cl-/SO 4 2-salt obviously increased soil EC, but adversely affected soil biological activities including soil invertase activity, soil microbial biomass carbon (MBC) and substrate-induced respiration (SIR). Clsalt showed a greater deleterious influence than mixed Cl-/SO 4 2salt on soil enzymes and MBC, e.g., the higher soil MBC consistently appeared with Cl-/SO 4 2-instead of Cltreated soil. Meanwhile, we found that SIR was more reliable than soil basal respiration (SBR) on explaining the changes of soil biological activity responsive to salt disturbance. In addition, microbial community structures of the soil bacteria, fungi, and Bacillus were obviously affected by both salt types and soil EC levels, and its diversity increased with increasing of mixed Cl-/SO 4 2-salt rates, and then sharply declined down after it reached critical point. Moreover, the diversity of fungal community was more sensitive to the mixed salt addition than other groups. The response of soil physiological profiles (Biolog) followed a dose-response pattern with Cl-(R 2 =0.83) or mixed Cl-/SO 4 2-(R 2 =0.89) salt. The critical threshold concentrations of salts for soil physiological function were 0.45 dS/m for Cland 1.26 dS/m for Cl-/SO 4 2-, and those for soil microbial community structural diversity were 0.70 dS/m for Cland 1.75 dS/m for Cl-/SO 4 2- .

Variation in Bacterial Community Structure in Rhizosphere and Bulk Soils of Different Halophytes in the Yellow River Delta

“…Recent studies have reported the characteristics of microbial communities in forest and farmland ecosystems (Teurlincx et al, 2018;Liang et al, 2019;Shao et al, 2019;Liu et al, 2021) and research on microbial communities in saline-alkali lands should be paid more attention. Salinity is one of the main factors affecting soil microbial diversity and composition in saline-alkali areas (Zhang et al, 2018;Yang and Sun, 2020;Zhao et al, 2020). The vegetation in saline-alkali areas is dominated by halophytes, which have an important impact on soil microbial communities (Cao et al, 2014).…”

Examining the impacts of salt specificity on freshwater microbial community and functional potential following salinization

“…This suggests that the initial microbial communities we might obtain might differ but will allow for an investigation of the generalizability of salt specificity on microbial community structures. We hypothesized that salt amendments differing in their ionic composition but at concentrations resulting in comparable natural freshwater‐specific conductance will have significant, albeit differential, effects on community α‐diversity (H1) and functional potential (H2) regardless of the state of origin (DeVilbiss et al, 2022; Zhang et al, 2018). We anticipated ‘core’ orders of each state to persist despite salt amendments, albeit at varying relative abundances, as these orders are generally associated with maintaining the basal functionality of the community (Custer et al, 2023; Shade & Handelsman, 2012).…”