An Exploratory Research on the Adoption of Different Phosphate-Solubilizing Fungi for Production of Phosphate Biofertilizers

Abstract Using the inherent capacity of the soil to meet the nutritional needs of plants is considered an efficient and environmentally friendly solution. In order to study the survival of different phosphate-solubilizing fungi in different combinations of rock phosphate and organic matter as the basis of biofertilizer with the aim of producing an effective formula of biological phosphorus granular fertilizer, this study was conducted as a factorial experiment based on a completely randomized design with three replications. For this purpose, after isolating phosphate-solubilizing fungal strains from agricultural soils in different regions of Iran (Fars, Kermanshah and Razavi Khorasan provinces), the superior strains with high growth stimulating capability were selected for bio-fertilizer formulation based on determination of fungi survival. In order to study the survival of the superior strains [including Talaromyces pinophilus strain 1FB, T. pinophilus strain MFA, Talaromyces verruculosus strain PF157-2 and Aspergillus tubingensis strain PF140-2], six levels of carrier including 100% rock phosphate, 80% rock phosphate + 20% organic matter, 60% rock phosphate + organic matter 40%, 40% rock phosphate + 60% organic matter, 20% rock phosphate + 80% organic matter and 10% rock phosphate + 90% organic matter were used in three temperature levels (28, 40 and 50 °C) during eight time periods (15 days, 30 days, 45 days, 60 days, 75 days, 90 days, 105 days and 120 days) under incubation condition. The results showed that based on the longer time of survival, and the instruction of Soil and Water Research Institute, Karaj, Iran, for the minimum acceptable number of phosphate solubilizing fungi in granulated phosphate microbial fertilizer, a granulated phosphate microbial fertilizer included each of the isolates (respectively PF 157-2 > PF 140-2 > MFA≫ 1FB), a carrier with at least 20% rock phosphate + at least 20% organic matter, and at the temperature of 28 or 40 °C may be developed and recommended in the agricultural soils as an environment-friendly source of phosphorus.