Microbial populations immobilizing NH4+-N and NO3−-N differ in their sensitivity to sodium chloride salinity in soil

An incubation experiment was conducted to study the response to sodium chloride (NaCl) salinity of microbial population immobilizing NH4+- and NO3−-N using glucose as an easily oxidizable C source. Immobilization of NH4+-N was faster than that of NO3−-N and was complete within 12 h of -incubation. Presence of NaCl retarded the process of N immobilization; that of NO3−-N being more affected. Remineralization of immobilized N started within 48 h in case of both NH4+- and NO3−-N and was faster for the latter. Both remineralization and nitrification were significantly delayed in the presence of NaCl; inhibition being more at 4000 mg NaCl kg−1 soil. The inhibitory effect of NaCl on remineralization of N was relatively more for NH4+-treated soil. The results of the study suggested a higher sensitivity to NaCl of microorganisms assimilating NO3−. However, remineralization of N from NO3−-assimilating microbial population was less affected by NaCl salinity compared to NH4+-assimilating population.