Under the influence of 2,5, or 10 μg/g atrazine, the degradation of 10 μg/g of the detergent n-dodecylbenzenesulfonate-14C to 14CO2 in an Alfisol soil is inhibited for about 12 days, then stimulated. The overall influence of atrazine after 38 days is a slight inhibition of 14CO2-formation.