Effects of Palm Oil Mill Effluent on Soil Microflora and Fertility in Calabar – Nigeria

Abstract

In the present study, an agricultural soil artificially amended with different concentrations of palm oil mill effluent was analysed to determine its impact on the soil microflora and other properties such as pH, organic matter, electrical conductivity, and mineral elements. In the polluted soils, the total heterotrophic bacteria, total heterotrophic fungi and total heterotrophic actinomycetes decreased significantly (p≤0.5) with increase in the concentration of the pollutant. The total heterotrophic bacteria and total heterotrophic fungi showed significant reduction (p≤0.5) with increase in the duration of the pollution while total heterotrophic actinomycetes showed no significance difference (p≥0.5) over the duration of pollution. Suspected bacterial isolates from the polluted soils were Pseudomonas sp., Bacillus sp., Staphylococcus sp., Micrococcus sp. Flavobacterium sp., Serratia sp., Proteus sp., while the suspected fungal isolates were Mucor spp., Penicillum spp., Aspergillus spp. and Rhizopus spp. There were significant differences (p≤0.5) in soil pH, organic matter, total nitrogen, potassium, magnesium, available phosphorus and base saturation of the polluted soil and that of the control while the values of sodium, calcium, exchangeable acidity and electrical conductivity of the polluted soil did not show significant difference with that of the control. There was rather a steady increase which was not statistically different from the control with increase in concentration of the pollutant. The results of this study revealed that soil polluted with little quantities of palm oil mill effluent could enhance microbial proliferation and thus, increase soil fertility, while a heavy application inhibits the same.