@ RK, yes, rhizospheric microorganisms like K solubilizing organisms such as B. mucilaginosus, B. edaphicus, B. circulans, Pseudomonas, Burkholderia, Acidithiobacillus ferrooxidans, Paenibacillus sp. etc. can solubilize the fixed form of soil K in the rhizosphere and bring more available K for plant nutrition. It can also breakdown the complex K compound in simpler form.

We may increase K availability in the soil after increasing soil moisture level that increases K movement to plant roots resulted more K in plant available form. That's why it is generally noticed more K fertilizer responses under dry condition or less rainfall years.

Rhizosphere microorganisms contribute significantly in solubilization of fixed forms of soil minerals K in the soil solution K. Potassium-solubilizing bacteria (KSB) are those bacteria that improve the growth and productivity of plants grown under salt-affected conditions via the breakdown of complex K compounds into simpler ones, hence making them available to plants. The potassium solubilizing microorganisms (KSMs) are a rhizospheric microorganism which solubilizes the insoluble potassium (K) to soluble forms of K for plant growth and yield. Higher soil moisture usually means greater K availability. Increasing soil moisture increases K's movement to plant roots and enhances availability. The rhizosphere conditions have a direct impact on crop growth and yield. Nutrient-rich rhizosphere environments stimulate plant growth and yield and vice versa. Extensive cultivation exhausts most of the soils which need to be nurtured before or during the next crop. It is known that potassium solubilizing bacteria (KSB) can solubilize K-bearing minerals and convert the insoluble K to soluble forms of K available to plant uptake. Many bacteria such as Acidothiobacillus ferrooxidans, Pae- nibacillus spp., Bacillus mucilaginosus, B. edaphicus, and B. These microorganisms solubilize K through the production of organic acids such as tartaric acid, citric acid, and oxalic acid to release K from its minerals. Apart from making potassium available, these microbes can improve soil health and crop yield and act as bio-control agents by producing antibiotics. Potassium ion homeostasis is essential for bacterial survival, playing roles in osmoregulation, pH homeostasis, and regulation of protein synthesis, enzyme activation, membrane potential adjustment and electrical signaling. The major way to increase K availability is to apply adequate amounts. Potassium is readily available from all these sources, provided they are located where roots can absorb the K. Rhizosphere microorganisms contribute significantly in solubilization of fixed forms of soil minerals K in the soil solution K. Inoculation of KSMs in soil has been shown to improve solubilization of insoluble mineral K resulting in higher crop performances. The rhizosphere harbors diverse microbial groups that perform various functions and exert numerous effects on plant growth. They are involved in nutrient cycling, protecting from phytopathogens as well as under biotic and abiotic stress conditions, and some may act as plant pathogens. Potassium solubilizing microorganisms (KSM) such as bacteria and fungi can solubilize K from an insoluble form to a soluble form to enhance uptake by plants. These microorganisms solubilize K through the production of organic acids such as tartaric acid, citric acid, and oxalic acid to release K from its minerals.