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The study was carried out at the Teaching and Research Farm of the School of Agriculture and Agricultural Technology, Minna, in the month of July 2014. The aim of the study was to estimate the bacteria and fungi population of three selected vegetation types at three soil depths and correlate microbial counts with the physicochemical properties of soils. The experiment was a 3 by 3 factorial experiment, arranged in a completely randomized design. The treatments were vegetation types (fallow, gmelina, and teak) and three soil depths (0–5 cm, 5–10 cm, and 10–15 cm). Data obtained were subjected to ANOVA while means were separated using the Student–Newman–Keuls test Linear relationship. The standard pour plate method was used to estimate bacteria and fungi colony-forming units (CFU) in 1 g soil. Physical and chemical analyses were carried out by standard laboratory methods. The bacterial and fungal counts were highest in the gmelina vegetation and least under teak. The 0–5 cm soil depth had the highest microbial counts. Bacterial population correlated positively and significantly with the fungal population and organic content while microbial population correlated negatively with soil pH. Gmelina vegetation produced the highest microbial population followed by fallow and teak in that sequence. Fallow recorded the narrowest C/N and C/P ratios, respectively, implying N mineralization and P solubilization while the tree vegetations recorded wider ratios signifying N and P immobilization. It can, therefore, be inferred from the results obtained that tree vegetations can be under cultivation with much sacrifice in inorganic N and P fertilizers. Fallow land, on the other hand, will require lower inorganic N and P inputs and, therefore, has prospects in reduction of environmental pollution and subsequent increase in crop production.