Exploring waste mica as an alternative potassium source using a novel potassium solubilizing bacterium and rice residue in K deficient Alfisol

Background and aims

Low-grade potassium (K) bearing minerals like waste mica and K-rich crop residues can be explored as an alternative K source. However, waste mica's low available K limits its efficacy. This study aims to use waste mica with a native K solubilizing bacteria (KSB) isolated from Alfisols near mica mines along with rice residue to enhance K availability in a K deficient Alfisol.

Methods

A novel KSB (JHKSB4), identified as Acinetobacter sp was isolated from soils of mica mining areas in Jharkhand, India. An incubation and pot experiment were conducted using JHKSB4, waste mica and rice residue in a K-deficient Alfisol to assess the release of K fractions and K recovery percentage.

Results

Incubation study revealed that waste mica with JHKSB4 and rice residue significantly increased the water-soluble K and exchangeable K contents in soil over mica alone. Pot experiment revealed that combination of mica, JHKSB4 and rice residue could increase 43-61% K uptake by wheat over control but could not exceed the impact of muriate of potash (MOP). Residual impact of this treatment was also observed on K recovery in rice crop. The changes in surface morphology of mica through scanning electron microscopy indicated dissolution of waste mica due to action of JHKSB4 and rice residue.

Conclusions

This study established the potential of waste mica treated with JHKSB4 and rice residue as a supplementary K-source for crops. It recorded a K recovery of about 33% of that achieved with MOP. Thus, use of biologically treated waste mica could be a gamechanger in the realm of sustainable K management by partially replacing MOP.