Assessment of Agricultural Water Pollution from Pesticide Runoff in Vegetable Farms in Ogun State

This study assesses pesticide runoff from intensive vegetable farms and its implications for agricultural water pollution in Ogun State, South West Nigeria. Intensive vegetable production in Ogun State involves high pesticide application rates to control insects, diseases, and weeds, with significant potential for pesticide runoff and leaching to affect adjacent water bodies and irrigation sources. Understanding pesticide transport pathways and contamination levels is important for assessing food safety and environmental risks in Nigeria's most agriculturally intensive southwest zone. This study uses a field monitoring design, collecting water samples from runoff plots, drainage channels, and irrigation water sources adjacent to intensive vegetable farms in Sagamu, Ifo, and Ado-Odo local government areas. Samples are collected during and after rainfall events over two cropping seasons. Pesticide residues are analysed using gas chromatography for organophosphate and pyrethroid compound classes. Water quality parameters including pH, turbidity, dissolved oxygen, and nitrate are also measured. Findings reveal detectable organophosphate pesticide residues in 68 percent of drainage channel samples and 42 percent of irrigation water samples, with concentrations exceeding WHO drinking water guidelines in 23 percent of samples. Chlorpyrifos and cypermethrin are the most frequently detected compounds. Application-to-runoff intervals below 48 hours generate the highest residue loads. The study concludes that pesticide water pollution is a significant environmental risk in Ogun State intensive vegetable areas and recommends integrated pest management adoption and vegetated buffer strip establishment.

Keywords: pesticide runoff, water pollution, vegetable farms, Ogun State, agricultural chemicals.