The Impact of Long-term Cassava Mill Effluent Discharge on Soil pH and Microbial Characteristics in Cross River State

Abstract

Increasing level of cassava effluent discharge on agricultural soils has become a source of concern for environmentalists including soil scientists. Therefore, this study assessed the impact of such activities on soil pH and microbial characteristics. The result obtained showed that the soil samples collected after 25 m away from the point of effluent discharge were slightly acid to slightly alkaline in pH, while those at the point of effluent discharge up to 10 to 25 m away from the point of effluent discharge were acidic. This showed that cassava mill effluent discharge increased soil acidity which could suppress bacterial growth in the soil within the point of discharge. The control soil had the highest microbial count than the impacted soils. The microbial species isolated included bacteria such as Lactococcus lactis, Bacillus subtilis, Pseudomonas aeruginosa, Micrococcus variance and Staphylococcus aureus while the fungal isolates include Aspergillus niger, Fusarium spp, Penicillium spp, Mucor spp and Rhizopus spp. The result further showed that in impacted soil Bacillus subtilis (27.78%), and Rhizopus spp (28%) had the highest frequency of occurrence for bacteria and fungi respectively while in the control soils Lactococcus lactis (26.67%), and Rhizopus spp (27.27%) and Penicillium spp (27.27%) were the most dominant bacteria and fungus isolated across the different sampling distances. Hence, there should be an increasing awareness of the emergency created by cassava processing mills and management practices should be adopted to remediate the impacted soil.