The Integration of Vermicompost, Plant Growth-Promoting Rhizobacteria and Amino Acid under Seasonal Variations Improve Soil Biological Properties and Maize Crop in Saline Soils

Abstract

Improving the soil quality in arid saline soils requires a greater understanding of how the vermicompost, rhizobacteria and seasonal variations affect the soil biological properties and maize yield. Two field experiments were conducted during spring and autumn seasons of 2021   to study the effect of interaction between vermicompost, amino acid and plant growth-promoting rhizobacteria (PGPR; Azotobacter chroococcum on   some soil properties and grain yield of maize   in saline soils for different seasons. The vermicompost was added at two levels (0 and 17 ton ha^-1)   while the amino acid was added at two concentrations (0 and 2500 mg L^-1), whereas the   Azotobacter was inoculated at two levels (0 and 10 ml).   The results showed that the vermicompost improved soil microbial biomass carbon (MBC) more profoundly in the spring season (9673 mg Kg^-1 soil) as compared to autumn season (3361 mg Kg^-1 soil). Whereas, higher Azotobacter number was found in autumn (19.75 x 10⁶ CFU g Kg^-1 dry soil) as compared to spring   (0.14 x 10⁶ CFU g Kg^-1 dry soil ) respectively.   In addition, the inoculation of Azotobacter significantly enhanced   MBC more pronouncedly in the spring season (7494 mg Kg^-1 soil) as compared to autumn season (3361 mg Kg^-1 soil). It was noticed a significant increase in phosphor content in plant after inoculation of bacteria at autumn season (0.35%)   as compared to spring season (0.20%).  Furthermore, the vermicompost, azotobacter and amino acid improved crop yield in both seasons but the improvements looked higher at the autumn season. In conclusion the interaction of vermicompost, amino acid and Azotobacter had significant effect on soil biological properties, and the grain yield at the autumn season was better than the spring season, which was associated with a typical increase in the number of Azotobacter and an increase in the phosphor content of plant and also associated with a decrease in the soil salinity.