Soil Rhizosphere pH, Enzymatic and Microbial Activities Under Different Nitrogen and Sulfur Fertilization of Soybean (Glycine max L.)

The soil rhizosphere pH, enzymatic activities (dehydrogenase, β-glucosidase, and arylsulfatase), microbial respiration rates, soil microbial biomass-C, soil microbial biomass-N and soil microbial biomass-S were used to monitor the impact of nitrogen (N) and sulfur (S) applications. The randomized block design experiment was conducted comprised fourteen treatments, varying N and S applications in timing and quantity at specific growth stages, with three replications. The results showed a significant increase in soil enzymatic and microbial activities after incorporation of N and S in the soil. The research highlights the efficacy of N and S (25 N kg ha^− 1 as basal + 25 N kg ha^− 1 at the R₂ stage + 12.5 S kg ha^− 1 as basal + 12.5 S kg ha^− 1 at the R₂ stage) in enhancing crucial variables, dehydrogenase, β-glucosidase, and aryl sulfatase activities, alongside microbial respiration and microbial biomass-C, N, and S during soybean growth at R₂ and R₅ stages. Notably, N treatments consistently lowered rhizosphere pH, with significant decreases observed, and combined N and S treatments also contributed to pH reductions compared to controls, while sulfur-only treatments maintained similar or slightly lower pH levels. Incorporating N and S boosted soil enzymatic and microbial activities while decreasing pH, with split dosing of N and S enhanced key variables in soybean, underscoring the intricate interactions between nutrients and soil dynamics. These findings provide valuable insights into optimizing nutrient management practices for improved soil health and crop productivity.