KINETIC FORMULATION OF THE DENITRIFICATION PROCESS IN SOIL

Abstract

Kinetic formulation of denitrification process in soil was developed based on a model of competitive Michaelis-Menten type enzyme kinetics. Several values of parameters were chosen to plot the concentrations of NO − 3 , NO − 2 , N 2 O-N and N 2 -N at various times of incubation under different initial concentrations of NO − 3 . According to the model the disappearance rate of NO − 3 was found to be independent of initial concentration of NO − 3 and was nearly constant, similar to zero order rate of disappearance. The initial rate of NO − 2 formation was independent of the NO − 3 concentration. However, the maximum concentration of NO − 2 and the time at which the maximum was found were found to be dependent upon the NO − 3 concentration. When there was very little accumulation of NO − 2 in the system, the initial rate of N 2 O formation was found to be independent of NO − 3 concentration. However, if there was high accumulation of NO − 2 , the initial rate of N 2 O formation became inversely related to NO − 3 concentration. The initiation of N 2 formation was generally slower as the concentration of NO − 3 increased. The composition of gas mixture, N 2 O and N 2 , was found to vary depending upon the initial NO − 3 concentration and with the time of incubation. The formulation presented herein describes the features of denitrification experimentally observed fairly well.