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Research article2022Peer reviewedOpen access

Optimization of Biofertilizer Formulation for Phosphorus Solubilizing by Pseudomonas fluorescens Ur21 via Response Surface Methodology

Barin, Mohsen; Asadzadeh, Farrokh; Hosseini, Masoumeh; Hammer, Edith C.; Vetukuri, Ramesh Raju; Vahedi, Roghayeh


This study aimed to analyze and quantify the effect of different ratios of vermicompost, phosphate rock, and sulfur on P solubilization and release by Pseudomonas fluorescens Ur21, and to identify optimal levels of those variables for an efficient biofertilizer. Twenty experiments were defined by surface response methodology based on a central composite design (CCD), and the effects of various quantities of vermicompost, phosphate rock, and sulfur (encoded by -1, 0, or +1) on P solubilization was explored. The results show that the CCD model had high efficiency for predicting P solubilization (R-2 = 0.9035). The strongest effects of the included variables on the observed P solubilization were linear effects of sulfur and organic matter (vermicompost), a quadratic effect of phosphate rock, and an interactive effect of organic matter x phosphate rock. Statistical analysis of the coefficients in the CCD model revealed that vermicompost, vermicompost x phosphate rock, and phosphate rock x phosphate rock treatments increased P solubilization. The optimal predicted composition for maximal P solubilization by P. fluorescens Ur21 (at 1684.39, with more than 90% of the added phosphate dissolved) was 58.8% vermicompost, 35.3% phosphate rock, and 5.8% sulfur. ANOVA analysis confirmed the model's accuracy and validity in terms of F value (10.41), p value (<0.001), and non-significant lack of fit.


biofertilizer; central composite design; modeling; phosphate solubilizing bacteria

Published in

2022, Volume: 10, number: 4, article number: 650Publisher: MDPI

    UKÄ Subject classification

    Soil Science

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