Effects of microbial bio-fertilizers on soil physicochemical properties under different soil water regimes in greenhouse grown eggplant (Solanum Melongena L.)

The aims of this research were to investigate the effects of microbial bio-fertilizer (BF) application on physicochemical properties of sandy-clay-loam (SCL) soil under three different soil moisture regimes in greenhouse-grown eggplant (Solanum melongena L.). Correlations between the physicochemical soil properties in a greenhouse condition were determined. The microbial bio-fertilizers included Azotobacter chroococum and Azotobacter vinelandii. Experiments were conducted in randomized plots design with three replications. Three different irrigation levels (100% (I100), 60% (I60) and 40% (I40) of field capacity-FC) were applied. Post-harvest soil samples were analyzed for soil physical and chemical characteristics. Bio-fertilizers had positive impacts on physicochemical soil properties. Bio-fertilizers accelerated mineralization of organic residues, thus improved the availability of macronutrients (N, P, K, Ca, and Mg) and micronutrients (Fe, Mn, Zn, and B). The highest total N value (0.143%) was observed in I100 treatment of bio-fertilizer (BF+I100) and the lowest total N (0.087%) was observed in I40 treatment without bio-fertilizer. Bio-fertilizers improved aggregate stability, total porosity, moisture-retention capacity and infiltration rate, and decreased bulk density of the soils. Bio-fertilizers increased water uptake and decreased drought susceptibility of the plants. It was concluded that bio-fertilizers could reliably be used to improve soil physical and chemical characteristics under different irrigation levels.