Augmenting the elemental sulphur-based formulation with Pseudomonas veronii: a haloalkaliphilic heterotroph for improved sodic soil reclamation and crop performance

The activity of native sulphur-oxidizing microorganisms is a key determinant of the success of elemental sulphur (S°)-mediated reclamation strategies for sodic soils. Enhancing sulphur oxidation through effective microbial inoculants can improve soil chemical properties and crop productivity under sodic conditions. This study evaluated the S° oxidation and crop performance of rice and wheat under sodic soils amended with S° and Pseudomonas veronii strain 43UP1, isolated from barren sodic soils. The P. veronii strain 43UP1 exhibited appreciable production of ammonia and indole-3-acetic acid, and P and Zn solubilization. For the first time, this isolate with S° oxidation activity was reported from sodic soils. It tested negative for hemolytic, DNase, and gelatinase activities. The P. veronii strain 43UP1 inoculation caused a 23–33% increase in the S° oxidation. It was associated with a decline in the HCO 3 ⁻ and total alkalinity. Increased S°-oxidation also increased Ca 2+ and Mg 2+ concentrations in the soil solution by 6.6–10.8% and 3.7–19.2%, respectively. It had appreciable capability to produce siderophores, indole-3-acetic acid (IAA), ammonia, hydrogen cyanide, and biofilm. The 43UP1 harbors soxA , soxB , and s oxY genes of the sox gene cluster. Inoculation of P. veronii strain 43UP1 with S° caused a 9.2–37.1% increase in rice and wheat yields compared to S° treatment alone. The pH, electrical conductivity, Ca 2+ and Mg 2+ in rice and soil organic carbon, and the sodium adsorption ratio in wheat were the key factors affecting inoculation response. This study concludes that the Pseudomonas veronii strain 43UP1 had potential for S° oxidation and plant growth promotion under sodic soil conditions. It can be effectively integrated with S° for crop nutrition and soil reclamation in sodicity-affected agroecology.