Microbial Biofertilizers and PGPR Enhance Soil Fertility, Nutrient-Use Efficiency, and Crop Productivity for Sustainable Agriculture

Abstract

: The aim of this study was to assess the potential of microbial biofertilisers and plant growth promoting rhizobacteria (PGPR) in improving soil fertility, nutrient-use efficiency (NUE) and productivity of the crops and minimising the use of synthetic fertilisers. As a hypothesis, we suggested that soil microbial activities, root development and nutrient use efficiency could be improved with the inoculation of beneficial microorganisms for sustainable production of crops. The experiment was laid out on 18 agricultural research farms over the three consecutive cropping seasons, comprising 360 experimental plots in Randomised Complete Block Design with three replications. Ten microbial treatments were tested, comprising seven microbial treatments, namely the control, rhizobium, azotobacter, azospirillum, phosphatesolubilising bacteria, potassiumsolubilising bacteria, arbuscular mycorrhizal fungi (AMF), biofertiliser + organic manure and biofertiliser + integrated nutrient management (INM). ANOVA, Tukey's HSD, Pearson correlation, multiple linear regression and Principal Component Analysis were used for statistical analysis. Results showed that the use of microbial biofertiliser and PGPRs led to an increase in soil MBC by 29.8%, soil nutrient availability by 27.4%, root development by 25.9% and the yield of the crop by 26.7%. Microbial biomass carbon (standardised β = 0.47, P < 0.001) and nutrient availability (standardised β = 0.42, P < 0.001) were the top two drivers of crop productivity when considered together in a multiple linear regression accounting for 77.8% of the variance in the response. Based on Principal Component Analysis, three different components were identified, which explained 84.4% of all variance – corresponding to soil microbial activity, plant growth and resource-use efficiency.