Assessment of pesticides residue in selected arable farm lands in Ogbomoso South local government area of Oyo state, Nigeria

Abstract. Pesticide residues in soils and farmlands have long been an important concern in agricultural safety. In developing countries, ignorance and illiteracy among untutored farmers have greatly contributed to this issue, as several pesticides (herbicides, insecticides, etc.) can leave residues in the soil. The study was carried out in selected arable farms in Ogbomoso South Local Government Area of Oyo state to evaluate and determine the possibility of pesticide residues in the soils of farmers who are fond of using pesticides in crop production. Questionnaires were administered to farmers in the study area and soil samples were collected from some of the farms owned by farmers interviewed and found to have relevant pesticide usage history. Additionally, soil samples were collected from farms with no records of pesticide usage which served as control. Subsequently, these soil samples were then taken to the laboratory for analysis of pesticide residue. The average pH was 5.56 mg/kg for farmlands with pesticide usage and 5.63 mg/kg for those with no pesticide usage, respectively. The average level of metabolites of d-BHC, Chlorothalonil, Alachlor, Aldrin, Dacthal, Heptachlor epoxide, g-Chlordane, and Trans-nonachlor for arable lands where there was pesticide usage and where none were used were 32.41 mg/kg and 39.27 mg/kg, 0.62 mg/kg and 1.05 mg/kg, 1.39 mg/kg and 2.14 mg/kg, N.D and 1.5 mg/kg, 3.91 mg/kg and 10.65 mg/kg, 5.43 mg/kg and 7.62 mg/kg, 6.68 mg/kg and 7.47 mg/kg, and 4.78 mg/kg and 6.4 mg/kg, respectively. The results showed that pesticide usage left residues in the soil and the standard of measuring the amount (whether low or high) is still unavailable in the literature and most importantly for many herbicides in use within the study area. Since there is a leftover chemical residue in the soil, there is therefore the need for a quality assurance body to evaluate what is placed on the table of consumers from the markets and this is currently lacking in the food supply chain in Nigeria and if not in Africa. In conclusion, there is a need for public awareness and education among farmers to know the dangers inherent in the use of pesticides so that precautionary measures will be taken in the application of pesticides.