COMPARATIVE ASSESSMENT OF AEROBIC CELLULOLYTIC BACTERIAL POPULATIONS IN EARTHWORM CASTS AND SURROUNDING SOILS ACROSS SELECTED SITES WITH VARYING PLANT COVERC.B. OGBONNA, D. P. BEREBON AND E.E. EBODE
Earthworms are soil dwellers that have profound effects on soil ecosystem. Their feeding and burrowing activities help to incorporate soil particles with organic matter and redistribute them back into the soil through their casts. The casts produced enhance microbial activities in soil that promote nutrient cycling. This study was carried out to compare the population and distribution of aerobic cellulolytic bacteria in earthworm casts against surrounding soils across selected sites within the Imo State University main Campus, Owerri. Four Habitats (A, B, C and D) were selected, composite soil and cast samples were then collected and the level of cast production (gm-2) was determined. After analyzing some physicochemical properties of the samples, the total number of aerobic bacteria (in nutrient agar medium) and aerobic cellulolytic bacteria in (cellulose agar medium) were counted. Our result showed a higher casts production in Habitat A (15.30±3.10 g-2) than in Habitat B (12.50±3.60 g-2), followed by Habitat C (10.80±4.20 g-2) and Habitat D (9.50±2.30 g-2), respectively. Casts recorded higher pH values, moisture, organic matter, total N, P, K and Ca contents in all the study sites. Casts also exhibited higher number of total aerobic bacteria (TAB) and aerobic cellulolytic bacteria (ACB), and bacteria cellulolytic activity compared to the surrounding soils in all the study sites. However, the quality of cast (and soil) decreased across the study sites (from Habitat A to D). The study suggested that earthworm cast could improve the physicochemical as well as microbiological properties of soil.
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