Impact of Pesticides Residues on Soil Bacterial Populations in Selected Communities of Ondo South, Nigeria

Abstract

Adeyemo I. A and Adoide R. B

Farmers use natural and synthetic pesticides to protect crops against rodents, insects, and disease-causing microbes. With an increasing human population, large quantities of pesticides are used to control pests and increase food yields. Pesticides have been linked to numerous environmental problems, including water, soil and air contaminations, biodiversity loss, and pest resistance. Despite the known risks, farmers in most nations are increasing their pesticide use. This study aims to evaluate the amount of pesticides in selected soil samples and its impact on the microbial population of the soil. Soil samples from ten communities designated A to J were collected with soil auger from tillage and rooting depth of plants (0 – 21cm) into sterile polytene bags in triplicates. Cultural, morphological and biochemical reactions were used for bacterial identification, while Gas Chromatography - Mass Spectrometry (GC-MS) was used in the pesticide analysis. In the control community (OAUSTECH), bacterial population range from 90.00 x 105 ±0.00 cfu/g to 92.67x 105±0.58cfu/g across the eight locations while the population ranged from 16.67x105 ±1.16 to 71.33 x 105 ±1.16 in the treatment communities. The bacterial number in the treatment communities differ significantly (P < 0.005) compared to the control. For pesticide analysis, Endosulfan ether range from 0.01 ±0.006ppm to 0.04 ±0.006ppm; Dieldrin from 0.03±0.0012ppm to 0.05 ±0.0010ppm; a P-DDT from 0.03 ±0.0012ppm to 0.06±0.0025ppm and Endrin ketone from 1.20 ±0.0037ppm to 2.06 ±0.015ppm. The results of this study, which show that pesticides negatively affect soil microbial populations, validate and support current environmental concerns.

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