Effects of the Herbicide Barban and its Commercial Formulation ‘Carbyne’ on Nitrification in Soil*

Abstract

Nitrification in soil was inhibited for at least 18 weeks following treatment with 200 parts/106 barban, either alone or formulated as Carbyne. During this time, neither Nitrosomonas nor Nitrobacter spp. could be detected in the soil. Periodic introduction of fresh soil failed to re‐establish nitrification, even with NH4+‐N supplementation. The solvent fraction of Carbyne inhibited nitrification only during the first two weeks. 3‐Chloroaniline, a metabolite of barban detected in soil treated with barban or Carbyne, caused only a temporary inhibition of nitrification at 50 parts/106. The presence of barban, either alone or in combination with solvent as Carbyne, appeared essential for the full and prolonged inhibition of nitrification.