Kinetics of disappearance of Metolachlor, Atrazine and Cyanazine residues in corn cultivation soil under the influence of fly ASH

The influence of fly ash, the lignite after burning remaining in thermal stations, on the fate of metolachlor, atrazine and cyanazine was studied in an experimental corn cultivation soil, under environmental conditions of Ioannina region (N.W. Greece). An amount of fly ash equal to 0.15% p.w. of soil for a depth 0–10 cm was used in a clay soil on the 18th of June 1991 when the sowing of the corn took place. The herbicides metolachlor, atrazine and cyanazine were applied six days later. Analyses of soil samples for 202 days period, between June 24 1991 and January 12 1992 made it possible to study the kinetics of decrease which is described satisfactorily employing a first order equation. The results showed that corn plantation and the addition of fly ash decreases the half life of herbicides as compared to the control fields as follows: For metolachlor from 45 to 34 and further to 25 days, for atrazine from 73 to 67 and further to 55 days and for cyanazine from 28 to 22 and further to 18 days. The percentage change in the rate constants of the equations corresponding to each herbicide and caused by the corn cultivation or the simultaneous corn cultivation and addition of fly ash, shows a fairly linear relationship with the water solubilities of three herbicides.