Microbial populations immobilizing NH+4-N and NO-3-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 It 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. (c) 2006 Elsevier Ltd. All rights reserved.