Comparative Effectiveness of KSB, Chemical K Fertilizer and Biotite on Soil K-fractions and Rhizospheric Microbial Activities under Maize Crop (Zea mays L)

Soils contain more K than any other nutrient; nevertheless, most of the K is inaccessible for plant absorption. In crop production, chemical fertilizers have been associated with several unfavorable outcomes that have a significant detrimental influence on environmental sustainability. Potassium-solubilizing bacteria (KSB) solubilize K-bearing minerals and transform insoluble K into soluble forms, which can be absorbed by plants. Therefore, solubilizing insoluble K in a plant-available pool using K-solubilizing bacteria could be an alternative and viable way to sustain crop production and maintain good soil health. A field experiment was conducted to quantify the changes in rhizospheric K fractions and soil microbial activity in maize crops. The treatments comprised of T1: Control; T2: KSB1; T3: 50% RDK; T4: 75% RDK; T5: T5 75 % RDK+25% through Biotite+ KSB; T6: 75% RDK + 25% Biotite; T7: 50% RDK + 50% Biotite + KSB1; T8: 50% RDK + 50% Biotite; T9 100% RDK. In this study, it was found that combining 75% RDK+25% RDK with biotite and KSB resulted in a better crop yield than using 75% RDK+25% RDK through biotite alone. The recommended dose of potassium (RDK), microbes introducing biotite into soil, affects K dynamics in soil by improving water-soluble, exchangeable, non-exchangeable, and total K pools compared to fertilizer K. Therefore, bio-intervention with waste mica could be an effective and viable method for solubilizing insoluble K into a soluble form, which can be used as a K fertilizer to maintain crop yields and soil K.