a. 4 mg NO3-N/L applied.
b. 10 mg NO3-N/L applied.
Figure 5. NO3-N in the soil profile.
erage velocity of water movement. More-
Denitrification was based on first-order ki-
over, denitrification would be promoted by
netics and moisture content. The relatively
conservative denitrification rate used was
The soil was assumed to have three layers
within the profile.
The soil-water characteristics for the simu-
lation were described using an equation de-
Figures 47 show the output from these sim-
veloped by Green and Corey (1971) and us-
ulations. The concentration values for the output
ing coefficients from Windsor sandy loam
were derived using the same technique as used in
soil, B horizon, which is similar to the soil at
the short-term simulations. The WASTEN model
the Fort Dix site.
simulations indicated that, under the conditions
The plant uptake and evapotranspiration
used for the computer simulations, the NO3-N con-
were set to zero. Ultimately these two pro-
centrations in the soil solution leaving the upper
cesses will tend to reduce N levels in the soil,
150 cm of the soil profile would not exceed 2.0 mg/
either by direct uptake or by increasing the
L. This was true for both application rates: 4.0 and
conditions that promote denitrification. Set-
10.0 mg/L NO3-N in the wastewater (Fig. 4a and
ting coefficients for evapotranspiration and
b). Additionally, NO3-N output following 168 days
plant uptake of N forces the model to as-
of treatment (seven cycles each of 4.0 and 10.0 mg/
sume that N not lost by denitrification will
L NO3-N in the wastewater) showed NO3-N efflux
be lost as NO3-N leachate.
below 2 mg/L NO3-N (Fig. 4c).