Factors affecting nitric oxide and nitrous oxide emissions from ...

Figure 6.9 Calculated HNO2 concentration of different urine-N rates treatments over time (n = 3,
error bars are ± the s.e.m). ...............................................................................................145
Figure 6.10 Fluxes of NO-N (µg m -2 h -1 ) from different urine-N treatments (n = 3, error bars are ±
the s.e.m)..........................................................................................................................147
Figure 6.11 Mesh plot of mean NO-N flux versus time and urine-N rates excluding control............147
Figure 6.12 Cumulative NO-N emitted as % of N applied versus urine-N rate and NH4 + -N
depletion rate (n = 3, error bars are ± the s.e.m).........................................................148
Figure 6.13 Daily NO-N flux rates as a percentage of mean net NH4 + -N depletion rates at different
urine-N rates (n = 3, error bars are ± the s.e.m)...............................................................150
Figure 6.14 Daily NO-N flux rates as a % of mean net NH4 + -N depletion rate versus bulk soil pH
for days 19-25. Numerals beside symbols are ‘day’ numbers.........................................151
Figure 6.15 Daily NO-N flux rates as a % of the mean net NH4 + -N depletion rates versus soil [H + ]
calculated using bulk soil pH for days 19-25. Numerals beside symbols are ‘day’
numbers. ..........................................................................................................................151
Figure 6.16 Fluxes of N2O-N (µg m -2 h -1 ) from different urine-N treatments (n = 3 replicates and
error bars are ± the s.e.m). ...............................................................................................153
Figure 6.17 Mesh plot of mean N2O-N flux versus time and urine-N rates excluding control...........153
Figure 6.18 Cumulative N2O-N emitted as % of urine-N applied over time for the urine treated
soils at different urine-N rates (n = 3 replicates and error bars are ± the s.e.m)..............154
Figure 6.19 N2O-N: NO-N ratio at different urine-N rates over time................................................155
Figure 6.20 Soil WFPS (%) over time for the urine-N treatments (n = 3, error bars are ± the s.e.m).156
Figure 6.21 Best fit regression models developed at day 21 (a) and for the 750 kg N ha -1 (b)
treatment during the experimental period (see Tables 6.8 and 6.9).................................160
Figure 6.22 The relationship between urine-N rates versus mean NO-N flux expressed either as the
% of the NO2 - -N pool being turned over per hour or as the % of the net NO3 - -N
accumulation rate ........................................................................................................166
Figure 7.1 Soil NH4 + -N concentrations over time (n = 3, error bars are ± s.e.m.)............................173
Figure 7.2 Soil NO2 - -N concentrations over time at 3 depths in the summer field experiment (a)
0.0-2.5 cm (b) 2.5-5.0 cm, (c) 5.0-7.5 cm (n = 3, error bars are ± s.e.m.)......................175
Figure 7.3 Soil NO3 - -N concentrations over time (n = 3, error bars are ± s.e.m.).............................176
Figure 7.4 Average net NH4 + -N depletion rate (ng g -1 soil h -1 ) in urine affected soil (n = 60,
number of samples used for each urine-N rate calculation). ...........................................177
Figure 7.5 Soil NH4 + -N: NO3 - -N ratios over time for the control and the urine treated soils (n = 3,
error bars are ± the s.e.m.) ...............................................................................................178
Figure 7.6 Soil pH over time following urine application (n = 3, error bars are ± the s.e.m.)..........179
Figure 7.7 Soil pH at 3 depths over time following urine application (a) 0.0-2.5 cm (b) 2.5-5.0 cm
and (c) 5.0-7.5 cm (n = 3, error bars are ± the s.e.m.). ....................................................181
Figure 7.8 Calculated HNO2 concentration in the control and urine treated soil at 3 soil depths (n
= 3, error bars are ± the s.e.m).........................................................................................183
Figure 7.9 Rainfall over the experimental period. ............................................................................184
Figure 7.10 Water-filled pore space over time (n = 3, error bars are ± the s.e.m.). ............................184
Figure 7.11 Soil temperature during summer field experiment at 7 cm depth....................................185
Figure 7.12 NO-N fluxes over time following urine treatment application (n = 3, error bars ±
s.e.m.). .............................................................................................................................186
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