A novel pyrimidynyloxybenzoic herbicide (ZJ0273) uniformly labeled with (14)C on the benzoate ring was applied to soils under sterile and nonsterile conditions to understand the effect of soil microorganisms and selected properties on its dissipation and transformations to bound resides and (14)CO(2). A significant effect of soil microorganisms was found in an acidic soil, where sterilization significantly prolonged the half-dissipation time (DT(50)) of ZJ0273 from 15.57 to 34.31 days and decreased the total amount of mineralized (14)CO(2) from 19.91 to 0.43%. However, sterilization showed limited effect on the patterns of bound residue or extractable residue levels in soils having pH > or = 6.1. In addition, a significant suppression of high pH was found on the dissipation of extractable residues and formation of bound residues. The enhancement of bound residue formation by low soil pH was attributed to increased conversion of ZJ0273 to its intermediates, which were rapidly bound to soil organic matter.