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.