The Influence of Cassava Mill Effluents on Soil Microbial Community in Akpabuyo, Cross River State, Nigeria

Abstract

The influence of cassava mill effluent on the microbial community of the soil was determined using viable counts method. Soil samples were collected from different sites (Locations A, B, C and D) impacted with cassava mill effluent, and also from sites unimpacted with cassava mill effluent, which served as control. The result of analysis of the impacted soil showed that the counts of Total Heterotrophic Bacteria, Total Coliforms and Total Fungi ranged from 2.0x103 CFU/ml to 2.3x104 CFU/ml, 1.9x102 CFU/ml to 1.5x104 CFU/ml and 1.4x102 CFU/ml to 2.2x102 CFU/ml respectively. These values were lower compared to the values (3.4x105 CFU/g to 3.6x106 CFU/g, 2.1x106  CFU/g to 3.3x106 CFU/g and 2.1x104 CFU/g to 3.0x104 CFU/g respectively) obtained from the unimpacted soils (control). The identification process of the isolates revealed the presence of the following bacteria; Bacillus spp., Micrococcus spp., Klebsiella spp., Pseudomonas spp., Staphylococcus spp., Salmonella spp. The fungal isolates from the effluents were identified to be Aspergillus spp., Rhizopus spp. and Mucor spp. The results obtained indicates that effluents from cassava mill effluent have a great impact on the microbial population of the soil. Since its application causes change that affects the microbial population and diversity, its continuous disposal could lead to decreased soil fertility and consequent low crop yield. Therefore, cassava mill effluents should be subjected to treatments that reduces their harmful substance content before disposal.