Microbial Population and Composition in Soils irrigated with Municipal Waste-water under Peri-urban Agriculture in Minna, southern Guinea Savanna Zone of Nigeria

Abstract

The source of irrigation water and its management have profound influence on soil microbial population and diversity with depth. This study was designed to determine the effect of soil depth, soil physical properties and source of irrigation water on microbial population under peri-urban Agriculture in Minna, Niger State. The experiment was based on 4 by 3 factorial combination in a complete randomized design(CRD) ie soils from 4 sites under different land uses (Keteren gwari Mechanic village, Chanchaga Bridge, Chanchaga Tributary and Morris Fertilizer) sampled at 3 soil depths of 0-5, 5-10 and 10-15 cm. Regression analysis was used to correlate the physico-chemical properties with microbial population and the experiment was subjected to two- way analysis of variance (ANOVA). The microbial population was estimated by using nutrient agar for bacteria, potato dextrose agar for fungi and caseine-asparagin agar for actinomycetes. Plate count method was used to estimate the colony-forming unit (c f u ) in g-1 soil. The mean of microbial population across the four sites indicated .that bacteria have the highest, followed by actinomycetes and fungi in that order. The highest microbial counts for the three groups of microorganisms were recorded at 0 to 5 cm depth and the lowest at 10 to 15 cm depth. The highest bacteria count (4.4 x 10 8 c f u g-1 soil) was obtained at Morris fertilizer while the highest fungi count (2.2 x 10 4 c f u g-1 soil) and the highest actinomycetes (3.0 x 10 8 c f u g-1 soil) counts were recorded at Keteren gwari. This study indicated that Chanchaga and Morris sites recorded the highest microbial count. The bacteria count ((4.4 x 10 8 c f u g-1 soil) and fungi count (2.2 x 10 4 c f u g-1 soil) were significant (p<0.05) at 0-5cm soil depth while the lowest microbial count was obtained at Chanchaga bridge and Chanchaga Tributary in which fungi count (2.2 x 10 4 c f u g-1 soil) was significant (p<0.05)