Penicillium pinophilum -based bio-mineral fertilizer comprising of rock phosphate and potassium feldspar enhances nutrient availability and fruit yield in pomegranate

High cost and poor use efficiency of phosphatic and potassic fertilizer calls for mobilization of fixed soil P and K through stimulated microbial activities. So, the study focused on the development of bio-mineral fertilizer (BMF) for enhanced fixed P and K solubilization and its impact on crop growth, nutrient dynamics in soil, plant and their relation with pomegranate fruit yield and quality. In-vitro studies followed by pot culture experiments and a field trial following randomized block design with four replications were conducted with different doses of BMF formulations to supplement chemical fertilizer use in pomegranate. Among various protocols attempted, introducing rock powder mixture into the carrier and sticking Penicillium pinophilum spores on to the surface with 1% sodium alginate solution was found to maintain the highest viable cell count of solubilizing microorganism and hence accepted for further evaluation in pot culture and field study. An application dose of 0.75 g kg−1 soil of BMF in a pot culture significantly increased the root biomass and N, P and K acquisition by plant than use of solubilizing bio-formulation. In orchard its’ application at the rate of 150 g tree−1 significantly enhanced availability of P and K in soil, subsequently improved foliar nutrition (N, Ca, Mg, S, Fe and Zn) during the fruit growth and increased fruit yield by 29.43% over application of bio-formulation. So, this bio-mineral fertilizer appears promising in supplementing synthetic P and K fertilizers to a great extent in arid and semi-arid region of the country.