[en] Study on degradation of herbicide dimefuron in soil by using bio meter flask experiment was conducted under laboratory condition, 14 C-dimefuron was applied to three conditions of sterile soil normal and bio fertilizer added soil. Every month ¹⁴ CO₂ was collected from 1 N KOH in bio meter flask with in eight months period. Carbon-14 activity was analyzed by liquid scintillation counter. The result of dimefuron degradation as ¹⁴ CO₂ in sterile normal and bio fertilizer added soil were 0.96 percent 6.31 percent and 9.36 percent. It can be concluded that increasing in dimefuron degradation rate was involved by micro-organism activity. After eight month extracted and bounded residue of dimefuron in soil were analysed. Radioassay show that extracted and bounded residue were 58.62 and 29.58 percent in sterile soil 45.73 and 41.91 percent in normal soil 45.28 and 36.3 percent in bio fertilizer added soil