Abstract Background: Spent Mushroom Compost (SMC), is a residual by-product of organic waste made up of plants, animals and fungi mycelia from a harvested mushroom fruits. Piled up of this waste create pollution and makes environment unhygienic for human activities. Research had it that, input of chemical fertilizers to increase soil fertility by farmers is detrimental to the environment and our health. Thou, SMC, the carrier contain fungi mycelia and trace of carbon source which serve as soil amender and organic fertilizer to improve plant growth. The aim of this study is to test SMC whether is a suitable and effective carrier for soil amendment and bio fertilizer production using Azotobacter and Pseudomonas strain. The organisms are best known as Plant growth promoting rhizobacteria (PGPRB) which lives in our soil with great potential. Inoculation of these with SMC has help improve the nutrient recovery of the carrier material. Materials and Methods: Spent Mushroom sample was collected from FIIRO botanical garden Langtang North-Plateau state, and was transported to Microbiology lab. Nasarawa State University, Keffi, for further experiment. Samples were sterilized, allowed to cool before inoculation with mixed consortium of Azotobacter chroococcum and Pseudomonas fluorescens. Results: The following were recorded: Ca 31.437 %, K 12.36 %, P 11.201 %, Fe 3.000 %, Zn 2.211 %, Mg 2.102%, Mn1.311 %, Cu has 1.002 %, N 0.98% and the least was Mo having 0.137 % respectively. Similarly, Maximum water holding capacity was 94.77, organic matter 59.13 %, organic carbon 46.37 %, Carbon-Nitrogen ratio 46:1, moisture content 43.86%, pH.7.4 and the least Ash content having 6.01% respectively. Mean and standard deviation method was employed to find the average mean for the entire triplicate sample measured. Statistically, there was a significant difference in the value recorded because the P>0.05 Conclusion: Thus, SMC is therefore considered a suitable carrier for bio-fertilizer production.

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