Crop damage may occur after herbicide disposal in manure: A preliminary study

Six plant protection products (esfenvalerate, diflufenican, isoproturon, terbutylazine, chlorsulphuron, and metsulphuron-methyl) were added to pig and bovine liquid manure, and the degradation of the compounds was followed over a period of 57 (sulphonylureas) or 77 (other compounds) weeks. After 57 weeks more than 50% of the sulphonylureas remained in the bovine liquid manure, while 25% remained in the pig liquid manure. After 77 weeks >90% terbutylazine, 50-60% enfenvalerate, and 10-40% diflufenican and isoproturon had been degraded in both bovine and pig liquid manure. With exception of terbutylazine, the examined plant protection products were neither quickly nor extensively degraded. The practice to add unused spraying liquid or rinse-water containing plant protection products to liquid manure constitutes a risk that unwanted compunds are inadvertently added to the fields when the liquid manure is used as fertilizer, and this may cause crop damage