Effect of potassium solubilizing bacteria and foliar application of potassium on soil nutrient status and soil biological properties in paddy (Oryza sativa) in coastal acid soils of Karnataka

Abstract

A field experiment was conducted to study the “Effect of potassium solubilizing bacteria and foliar application of potassium on uptake and nutrient use efficiency in paddy (Oryza sativa) in coastal acid soils of Karnataka” during the Kharif 2021 at Zonal Agricultural and Horticultural Research Station (ZAHRS), Brahmavar, Udupi, KSNUAHS, Shivamogga. The experiment was laid out in Randomized Complete Block Design with eleven treatments replicated thrice. The experimental treatments included combinations of recommended doses of nitrogen, phosphorus, and potassium along with soil application of KSB and foliar KCl. Results showed significant improvements in soil chemical properties in the treatment with a recommended dose of N and P₂O₅, 75% K₂O, KSB at 5 kg ha⁻¹, and 2% KCl foliar spray at 30 and 60 DAT (T10). Organic carbon increased to 1.56%, with available nitrogen, phosphorus, and potassium reaching 275.85 kg ha⁻¹, 65.76 kg ha⁻¹, and 129.10 kg ha⁻¹, respectively. Micronutrient availability also improved, with iron (20.53 mg kg⁻¹), manganese (4.80 mg kg⁻¹), zinc (2.63 mg kg⁻¹), and copper (4.47 mg kg⁻¹) significantly higher than the control. Biological properties were enhanced, with bacterial (30.07 cfu × 10⁵ g⁻¹ soil), fungal (43.75 cfu × 10³ g⁻¹ soil), and actinomycetes (19.80 cfu × 10² g⁻¹ soil) populations reaching their highest levels in T10. Potassium solubilizing bacteria populations were also maximized (42.78 cfu × 10² g⁻¹ soil), reflecting improved potassium availability. This study highlights the synergistic role of KSB and foliar potassium in enhancing soil fertility and microbial activity, offering a sustainable strategy for reducing chemical input dependency and improving paddy yield in acidic soils.