Effect of Halotolerant Microbial Inoculants on Anion Dynamics in Saline Soils

Key findings indicate that halotolerant bacterial consortia and single-strain inoculants are capable of reducing soil Cl⁻ by up to 11.10%, HCO₃⁻ by up to 9.89%, and SO₄²⁻ by up to 8.17% relative to uninoculated controls after 90 days of incubation. Nitrate dynamics were markedly influenced by salinity: denitrification rates declined by 50.08% under highly saline conditions (equivalent to ∸24 mS cm⁻¹), with parallel suppression of the functional denitrification genes nirK, nirS, and nosZ.

Microbial mechanisms identified include exopolysaccharide (EPS)-mediated cation bridging that displaces anion-associated sodium, ACC deaminase activity lowering ethylene and improving root access to anion pools, nitrogen fixation supporting soil N balance under NO₃⁻ depletion, and organic acid secretion altering anion speciation via pH buffering. Agronomic benefits including significant improvements in plant height, dry weight, grain yield, and K/Na ratios corroborated the soil-chemical improvements measured.

These findings establish a mechanistic framework for deploying halotolerant inoculants as targeted anion-regulating bioinoculants in salt-affected agricultural systems.