Insecticide Residues in Cotton, Sorghum and Fallow Soil from the Nuba Mountains Cotton Corporation of South Kordofan State, Sudan

BACKGROUND. Soil is the final depot of most environmental contaminants, including pesticides. Soil may be contaminated by pesticides as a result of direct application or drift during spray activities. Soil contamination with pesticide residues may affect the quality of food crops, animal products, and soil micro-organisms which may in turn negatively affect human health and the environment. OBJECTIVES. The main objective of the current study was to determine the soil residues of commonly used pesticides in rain-fed crops grown by the Nuba Mountains Cotton Corporation (NMCC) in South Kordofan state of Western Sudan. METHODS. Four locations (representing the four directions around the state capital Kadugli) were chosen for sample collection: Alefain (East Kadugli), Elmashaish (West Kadugli), Ed Dalling uncultivated area (North Kadugli) and Lagawa (Southwest Kadugli). Nine soil samples were randomly taken from each location representing areas under cotton, sorghum, and uncultivated land covered with natural vegetation. Soil samples were analyzed by gas chromatography (GC) equipped with electron capture detector (ECD) and GC-mass spectrometry (MS). RESULTS. The results generally indicated that organophosphate levels were greater than organochlorine and pyrethroids with heptachlor, malathion, and dimethoate present in all samples analyzed, while the level of p,p-dichlorodiphenyltrichloroethane (DDT) was below the detection limit. Endosulfan α and β isomers were detected in some samples. Dimethoate had the highest level (22.02 mg/kg), while β endosulfan was found at the lowest level (0.015 mg/kg). Generally, samples collected from cotton soils showed higher residue levels compared to sorghum soil with average concentrations of 307.25 mg/kg versus 58.63 mg/kg, respectively. Almashaish showed the highest residues levels followed by Alefain, Lagawa, and Ed Dalling with total residues of 57.56 mg/kg, 26.34 mg/kg, 22.63 mg/kg, and 17.07 mg/kg, respectively. CONCLUSIONS. The current study sheds light on the residue levels of some of the commonly used pesticides in the cotton rain-fed scheme in South Kordofan State, western Sudan. The study calls for regular residue monitoring in various environmental components in the area and suggests possible management measures. COMPETING INTERESTS. The authors declare no competing financial interests.