Effects of Salinity on Herbicide Lactofen Residues in Soil

Soil salinization is an increasing problem in agricultural soils on a worldwide scale. To assess the effects of salinity on the fate of herbicide lactofen in soil, laboratory degradation experiments were performed using soil with and without additional salinity. Lactofen and two major metabolites desethyl lactofen and acifluorfen were analyzed using HPLC-MS/MS. The degradation of lactofen and metabolites followed first-order kinetics with rate constants ranged from 0.30 to 0.35 day⁻¹ (estimated half-lives from 1.99 to 2.30 days) when additional salinity was not present. Lactofen concentration was greater in the salinized soil than in the control soil. The maximum concentrations of metabolites desethyl lactofen and acifluorfen were increased by 6.9 and 53% in salinized soil compared to control soil, respectively. The degradation of lactofen and metabolites was restrained by the application of salts and residues remained for a longer time in the salinized soil. Inappropriate management of soil and water resources may lead to the increase of salinity, which has the potential to enhance pesticides residues risk in soil.