Assessment of the Impact of Pesticides on Soil Quality in Rice-Growing Areas of Baguineda, Mali

The intensive use of pesticides in the rice-growing areas of the Baguineda Irrigated Perimeter Office (OPIB), as in several other rice-growing regions of Mali, is raising growing concerns about the environment and public health. This study was conducted to examine the impact of pesticide use on the quality of rice-producing soils, through an assessment of farmers' knowledge and practices and the detection and quantification of pesticide residues in soil samples. Preliminary surveys were conducted in four villages of Baguineda (Dougourakoro, Kognimba, Sebela, and Mofa) to identify the pesticides currently used by the farmers. These surveys involved 50 respondents with 15 farmers from Kognimba and Dougourakoro villages and 10 farmers from Mofa and Sebela. Subsequently, a sampling campaign collected 40 soil samples, which were analyzed at the Central Veterinary Laboratory in Bamako using an Agilent 7890 gas chromatograph. The surveys identified a list of 19 active pesticide substances currently used in the OPIB production area, including three herbicides, two fungicides, and fourteen insecticides. Four methods of managing empty pesticide packaging used by producers were also identified. Pesticide application practices, such as over- and under-dosing, were also observed. Among farmers, 33.5% follow the advice of OPIB supervisors on pesticide use, 44.5% rely on local distributors, while 12.25% follow the advice of their neighbors and 9.75% rely on their own experience, with none of them admitting to following the recommendations of pesticide manufacturers. These varied practices, including failure to comply with recommended dosages and lack of expert advice, contribute directly to soil contamination, as evidenced by the presence of three organochlorine pesticides (endosulfan α, endosulfan β, and lindane) and two organophosphates (dichlorvos and chlorpyrifos) in the samples analyzed. The concentrations measured, ranging from 0.008 to 0.28 mg.kg⁻¹, indicate that the soil is contaminated with pesticide residues, some of which are classified as persistent organic pollutants. This study highlights the need to continue adopting sustainable agricultural practices and raising farmers' awareness of the risks associated with the safe use of pesticides in order to preserve soil quality and public health in OPIB rice growing areas.