ABSTRACT

Biological potassium fertilizer (BPF) is a promising technology to improve potassium availability in the soil through the bio-activation of endogenous K-reserves. A group of microorganisms has been recognized for K solubilization from insoluble silicate minerals (e.g. biotite, feldspar, illite, muscovite, orthoclase and mica) and these microorganisms can potentially perform a key role in enhancing K supply to plants. This group of microorganisms includes both bacteria and fungi, commonly known as potassium-solubilizing microorganisms (KSMs). The KSMs have been found effective in solubilizing K (34–38% of the total K) from insoluble minerals by releasing organic acids. The efficiency of KSM in solubilizing native K reserves is highly dependent on the type of soil, nature of K bearing minerals and other soil environmental conditions. As far as the effect of KSM application on crop performance is concerned, the application of KSM improved crop yield by on average 17%, obtained from 20 greenhouse and 12 field trials. However, K-bearing minerals inoculated with KSM were found to be more effective in light texture soils with a crop having a long gestation period. This communication presents the K solubilizing potential of different KSMs and their application as BPF in agriculture as well as associated challenges behind large-scale adoption.