This present invention provides a method for spray tank cleanout. In particular, the invention further relates to a method for reducing residual sulfonylurea herbicide contamination of a spray tank from which the sulfonylurea is applied.本發明提供了一種噴霧桶清洗方法。尤其是,本發明亦涉及一種減少供施用磺醯脲之噴霧桶中殘餘磺醯脲除草劑污染物的方法。