AbstractThe present study is about the evaluation of the biological break down of the plant health products, the chemical compounds and heavy me tals in five (5) samples of soils taken from the fields of cotton, rice and cereals of CMDT and the Office du Niger area. The residues of pesticides were analyzed by gas chromatography after extraction and purification. The analyses revealed a contamination of the soils by the varying atrazine from 0,009 to 0,01 mg/kg, by the carbofuran and the varying endosulfan from 0,005 to 0,008 mg/kg. We notice the presence of eight (8) heavy metals (Ac, Cd, Pb, Al, Fe, Zn, Cr, Co) in all the samples of soils. The strong concentrations of Fe and Zn do not consti tute pollution, but they are of geological origin. A pol lution by Cd was observed: its concentration is 1,3 times (soil 4) and 1,5 times higher than the European standard (soil 2 and soil 5). The follow-up at the labo ratory of the degradation of the pesticides in various types of soils showed that this degradation is faster in the soils rich in organic matter and clay. The degra dation of biocides and heavy metals by the bacte rial communities can be in fluenced by environmental factors such as the pH, the temperature, the content of nutrients etc.
Keywords : Arable lands, Biological depollution, Mali, Promotional pro gram, Segou, Sikasso V alorization.