In vitro Evaluation of the Effect of Inorganic Fertilizer on Rhizosphere Soil Microbial Populations during Early Growth of Zea mays and Phaseolus vulgaris

Aims: The study assessed the effects of different regimen of inorganic fertilizers on the microbial community structure in the rhizosphere soil of Zea mays and Phaseolus vulgaris during early growth.

Study Design: Seeds of Zea mays and Phaseolus vulgaris were planted and Inorganic fertilizers were added to the soil after two weeks of planting to determine their effects on the microbial structure as well as the microbial succession pattern in the rhizosphere soils of Zea mays and Phaseolus vulgaris during early growth. Statistical analysis were carried out using a two-way ANOVA.

Place and Duration of Study: This study was carried out at the farmland of School of Agriculture and Agricultural Technology of the Federal University of Technology, Owerri Nigeria for a period of five weeks.

Methodology: Seeds of Zea mays and Phaseoulus vulgaris were planted in a soil under laboratory condition and different regimen of inorganic fertilizers added after two weeks using the placement method of fertilizer application, and a control experiment maintained without addition of fertilizers. Rhizosphere soil from Zea mays and Phaseolus vulgaris were collected every week for the remaining weeks for microbiological analysis to determine the microbial community and microbial populations present in the soil.

Results: In this study the presence of Bacillus sp, Staphylococcus aureus, Micrococcus luteus, Enterococcus faecalis, and Rhizobium sp, were evident in the rhizosphere soil of both Zea mays and Phaseolus vulgaris all through the five week period of study. The fungal community structure revealed the presence of Saccharomyces sp, Fusarium and Penicilium notatum for Zea mays rhizosphere soil, while Phaseolus vulgaris rhizosphere soil had Saccharomyces sp, Streptomyces sp, Fusarium and Penicilium notatum. The microbial succession pattern revealed that Bacillus sp, Staphylococcus aureus, Rhizobium sp and Saccharomyces sp were mostly predominant in the rhizosphere soil of Zea mays and Phaseolus vulgaris all through the period of study.

Conclusion: The results from this study revealed that inorganic fertilizers had significant effect on the microbial community structure present in the rhizosphere soil of Zea mays and Phaseolus vulgaris during early growth when compared to the control without inorganic fertilizer. This result suggests that the increased microbial community in rhizosphere soil of Zea mays and Phaseolus vulgaris resulted from increased biological interaction in the soils between the roots of plants, microorganisms and the inorganic fertilizer.