Nitrification Inhibition Using Benzotriazoles

ABSTRACT The common corrosion inhibitor, 1H-benzotriazole (Bz), found as a component of glycol-based aircraft deicers, and its derivatives such as 5-chloro-1H-benzotriazole (CBz), 1-hydroxy-benzotriazole (HBz), and 5-methyl-1H-benzotriazole (MBz), are all potential nitrification inhibitors. The inhibitory effect on the nitrification of urea-N fertilizer in agricultural soils was examined over a four-week period. All the compounds tested, except HBz, have the ability to inhibit the nitrification of urea-N fertilizer effectively. Their inhibitory capabilities depend on the structural components of the soil, particularly organic matter (O.M.). In the soil with the largest percent of O.M. (2.3%), inhibition by all the benzotriazole derivatives was considerably decreased. In the soil with least O.M. (0.3%), even HBz, the poorest of the inhibitors, showed signs of inhibition. For Bz, MBz, and CBz, in the range of 90% inhibition was observed in the soil with the lowest O.M. content during a four-week treatment period. On a mass basis, Bz had the greatest inhibitory effect followed by MBz and CBz, whereas HBz showed little inhibition of the nitrification of ureaN in soils with >0.5% O.M. If the inhibitory effects were looked at on a molar concentration basis, there would be little variation in inhibitory potency for MBz, CBz, and Bz. It was concluded that all three are effective nitrification inhibitors with urea-N fertilizer. The incorporation of benzotriazoles as inhibitors could help economize N fertilizers by helping prevent leaching and denitrification. However, the environmental fate of these compounds has not been determined, and they may produce toxicity to plants and other organisms.