Soil sorption and leaching of active ingredients of Lumax® under mineral or organic fertilization

•Sorption of Lumax active ingredients in a long-term manured soil was studied.•Mineral or organic fertilization affected soil sorption of Lumax active ingredients.•Desorption from soil managed with mineral or organic fertilization was hysteretic.•The leaching of Lumax was negatively correlated to its sorption.•The mineral fertilization enhanced Lumax active ingredients leaching.

The study describes the soil sorption of the herbicide Lumax®, composed of S-metolachlor (MTC), terbuthylazine (TBZ), and mesotrione (MST), as influenced by mineral and organic fertilizers. The investigation was performed on a sandy soil of an agricultural area designated as a Nitrate Vulnerable Zone, where mineral and organic fertilizers were applied for many years. Two organic fertilizers, cattle manure and slurry, respectively, and a mineral fertilizer with a nitrification inhibitor, Entec®, were compared. According to the experiments, performed with a batch method, the sorption conformed to Freundlich model. The extent of sorption of Lumax® ingredients was closely related to their octanol-water partition coefficient Kow. The respective desorption was hysteretic. Leaching trials were carried out by using water or solutions of DOM or Entec® as the eluants. Only the elution with the mineral fertilizer promoted the leaching of Lumax® active ingredients.