| Popis: |
The effect of 2,4-dichloro-6-(o-chloroanilino)-s-triazine (dyrene) and manganese ethylene bisdithiocarbamate (maneb) at 0, 15, 60, 240, and 960 ppm on nitrification of 100 ppm applied NH₄-N, and on ammonification of soil nitrogen, and the degradation of these fungicides, were studied in a lateritic clay and a fertile loam incubated at 24C for 16 weeks. Inhibition of nitrification by the fungicides was lesser and of shorter duration in the rapidly nitrifying loam than in the slow nitrifying lateritic soil. The chemicals inhibited the ammonia oxidizing bacteria but not the nitrite oxidizing bacteria. Maneb was several times more toxic to the nitrifying organisms than dyrene, and its effect lasted even after the chemical was degraded. Ammonification was inhibited only at 960 ppm of the fungicides. There was no synergistic effect with regard to inhibition of nitrification or ammonification when the soil received both the fungicides. The fungicides were degraded faster in the rapidly nitrifying soil than in the slow nitrifying soil. Maneb was decomposed earlier than dyrene. |
