The experiment consisted of 15 treatments (3x5), that is, three levels of ammonium sulphate CO, 100 and 200 ppm) and 5 levels of N-Serve (0, 1, 2, 4 and 8 pptn) , with three replicates. Samples of an alfisol were mixed with their corresponding treatments, placed in PVC tubes, and incubated during 160 days at a temperature between 269C-309C. After each leaching period with water, in a total of five leachings, the nitrate contents were determined. The data showed the nitrate contents in the treatments with N-Serve were lower than those without N-Serve. Better efficiency was obtained with the higher level, of nitrapyrin. The persistence of 2-chloro-6(trichloromethyl) pyridine in the soil increased with increasing levels of this inhibitor. After incubation period of 80 days, the effectiveness of N-Serve was completely reduced.