CONSECUTIVE STEADY STATE REACTIONS OF UREA, AMMONIUM AND NITRITE NITROGEN IN SOIL

Abstract

Previously developed mathematical models based on first and zero order sequential transformations of urea–nitrogen to nitrate by soil urease and microorganisms, based on Michaelis–Menten-type kinetics, were examined in a laboratory soil column with continuous flow. Comparison with data show that the models describe adequately concentration profiles of urea, NH4+, NO2− and NO3−. Apparent rate constants for urea hydrolysis and for NH4+ and NO2− oxidation increased with duration of flow. These increases in rate constants are attributable to microbial growth. A microbial profile developed in the column and was characterized by a decrease in population densities with depth.