Effect of Nitrapyrin on Mineralization of Urea and Isobutylidene Diurea in a Highly Organic Medium

Abstract

Mineralization of nitrogen fertilizers was determined in an organic medium composed of 6 pine bark : 3 sand : 1 soil (by volume). Nitrification was evident by day 7 following treatment with urea and isobutylidene diurea (IBDU) and increased rapidly after day 14. Nitrification was not evident until day 56 in medium treated with urea + nitrapyrin (NI). Medium treated with urea or IBDU were depleted of NH4+ within 1 month, which corresponded to a peak in NO2– + NO3– accumulation. Only a small amount of NH4+ was not accounted for by nitrification and was assumed to be adsorbed by bark particles. Chemical names used: 2-chloro-6-(trichloromethyl)pyridine (nitrapyrin), 1,1-diureido isobutane (IBDU).