Monitoring of Agrochemical Usage and Residue Management Practices Among Smallholder Vegetable Farmers in Plateau State

Smallholder vegetable farmers in North Central Nigeria are intensive users of agrochemicals, often applying pesticides and fertilisers without adequate technical guidance, raising concerns about food safety and environmental contamination. This study monitors agrochemical usage patterns, dosage practices, storage and disposal behaviours, and selected pesticide residue levels in three vegetable crops among smallholder farmers in Jos South and Barkin Ladi Local Government Areas of Plateau State. A structured questionnaire was administered to 120 farmers to characterise agrochemical use patterns. Soil and crop samples were collected from 30 farms and analysed for chlorpyrifos, cypermethrin, and atrazine residues by gas chromatography. Environmental contamination pathways including runoff and groundwater infiltration were assessed through soil leachate analysis. Results show that 68 percent of farmers mix multiple pesticides in a single application without checking label compatibility. Pre-harvest intervals are consistently disregarded, with 72 percent of farmers applying pesticides within five days of harvest. Chlorpyrifos residues were detected in 80 percent of collected tomato samples, with 22 percent exceeding the Codex maximum residue limit. Atrazine was detected in soil leachate from nine farms, indicating downward mobility toward groundwater. The study recommends mandatory farmer training on integrated pest management principles, establishment of pesticide residue monitoring at Plateau State markets, and review of over-the-counter pesticide sales regulation by the National Agricultural Chemicals Association of Nigeria. Keywords: agrochemicals, pesticide residues, smallholder farmers, Plateau State, food safety