ISSN:
1432-072X
Keywords:
Nitrification
;
Herbicides
;
Simulation
;
Inhibitors
;
Soil
;
Mathematical Model
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract The effect of 35 herbicides on the nitrification process was tested both by experiment, and by simulation of possible mechanisms of inhibition in a mathematical model. The model consists of nine equations with six coordinated constant and seven measurable parameters (or initial values), depending on the specific soil. The only free parameters are the initial values of the oxidative enzyme systems, and the parameters which determine the course of possible inhibition effects. For the majority of the herbicides, the inhibitory effects on the NH4 + or NO2 - oxidation were found negligible in the range of practical application. Hypotheses of a completely reversible or partially reversible inhibition of the oxidase systems gave the best correspondence between the model and reality, while an alteration of the growth parameters of the nitrifying populations in the model (death rate, proliferation rate, initial kill) due to the application of herbicides led to strong contrasts between simulated and experimental curves. Significant inhibitory effects became evident only when the hydrogen ion concentration in the soil fell below pH 7. Results with several herbicides indicated that the process of NO2 - oxidation was more sensitive than that of NH4 + oxidation. With a number of herbicides, an accumulation of NO2 - ions was noticed during the course of soil percolation. In consideration of the buffering capacity, the model is applicable to other soils.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00403068
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