THE FLORIDA STATE UNIVERSITY ARTS AND SCIENCES ...

1.7. Conclusion and suggested methods to predict the denitrification
rate
Principally two types of simplified denitrification models are frequently used and
described in literature, a) Simplified Models and b) Soil Structural Models. Calibration of
all the models required site specific data; once the models are calibrated they can be used
to estimate the denitrification rate to within an order of magnitude (Heinen, 2004),
However, none of the models can obtain an exact correspondence with the measured
data.
In addition to the need for calibration, the bulk of the models reviewed almost always
require a potential denitrification rate and this rate is usually determined by lab and field
measurements or by using existing models which consider denitrification as a function of
organic carbon or some other controlling factor. In many cases the attempt to establish a
potential denitrification rate in its self is a cost intensive exercise that defeats the purpose
of a quick, accurate and cost effective method to determine the rate of denitrification.
The majority of the models under consideration use a comparable simplified
denitrification model that assumes the actual denitrification rateto be a function of the
potential denitrification rate and several reducing functions. There is a general consensus
on the description of a universal mathematical function that can be used to explain
denitrification (Heinen, 2004) (Equation 1.12). There is, however, no agreement about
the importance of reduction functions and their values within any of the models unless
they are for the same study area and by the same author.
D = α f f f f
----- Equation 1.12
a
N
S
T
pH
As the functions and the values used in each of the models are empirically derived it is
difficult to agree upon a universal set of functions and values. It is thus difficult to obtain
an agreeable set of reduction function values for nitrate content, degree of saturation, soil
temperature, soil pH and other factors that control denitrification. The lack of consensus
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