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

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8.4.1 Prediction of NO-N fluxes. .......................................................................................................... 218 8.4.2 Prediction of N2O-N fluxes .......................................................................................................... 218 8.5 DISCUSSION ...................................................................................................................................... 219 8.5.1 Soil inorganic-N, moisture, temperature and pH dynamics ........................................................ 219 8.5.2 Theoretical HNO2, NO-N and N2O-N fluxes................................................................................ 220 8.5.3 Comparison with other in situ winter studies .............................................................................. 221 8.6 CONCLUSIONS................................................................................................................................... 222 Chapter 9 General conclusions and future work............................................................................................ 223 9.1 INTRODUCTION ................................................................................................................................. 223 9.2 WHY WAS NO NO2 FLUX MEASURED? ............................................................................................... 223 9.3 SOIL PH AND NO-N FLUXES.............................................................................................................. 223 9.4 SOIL TEMPERATURE AND MOISTURE AND NO-N FLUXES.................................................................. 224 9.5 N2O-N FLUXES.................................................................................................................................. 225 9.6 REGRESSION ANALYSES .................................................................................................................... 225 9.7 FUTURE STUDIES ............................................................................................................................... 226 References .......................................................................................................................................................... 227 x
List of Tables Table 2-1 Global Inventory of NO Emissions from Soils (Davidson & Kingerlee, 1997)..................4 Table 3-1 Physical and chemical characteristics of soil at the field site. ...........................................24 Table 3-2 Physical and chemical characteristics of soil used in the laboratory experiments.............25 Table 4-1 Bivariate correlation between measured soil variables and gaseous N (NO-N and N2O- N) fluxes for data sets pooled over time for the experimental period. ..............................33 Table 4-2 Bivariate correlation between measured soil variables and gaseous N (NO-N and N2O- N) fluxes for day 7.............................................................................................................33 Table 4-3 Bivariate correlation between measured soil variables and gaseous N (NO-N and N2O- N) fluxes for day 14...........................................................................................................34 Table 4-4 Bivariate correlation between measured soil variables and gaseous N (NO-N and N2O- N) fluxes for day 21...........................................................................................................34 Table 4-5 Bivariate correlation between measured soil variables and gaseous N (NO-N and N2O- N) fluxes for day 28...........................................................................................................35 Table 4-6 Bivariate correlation between measured soil variables and gaseous N (NO-N and N2O- N) fluxes for day 35...........................................................................................................35 Table 4-7 Net NH4 + -N depletion and net NO3 - -N accumulation rates in urine affected soil as influenced by initial soil pH treatments. (n = 15, number of samples used for each individual pH calculation). ................................................................................................38 Table 4-8 Correlation coefficients between the soil NH4 + -N: NO3 - -N ratio and initial soil pH treatment at each sampling time for the urine treated soil.................................................39 Table 4-9 Results of multiple linear regression for log10NO-N (µg m -2 h -1 ) of urine treated soils at individual sampling occasions across all initial soil pH treatments. .................................59 Table 4-10 Results of multiple linear regression for log10NO-N (µg m -2 h -1 ) of urine treated soils at different initial soil pH treatments over time.....................................................................59 Table 4-11 Results of multiple linear regression for log10N2O-N (µg m -2 h -1 ) of urine treated soils at individual sampling occasions across all initial soil pH treatments...............................60 Table 4-12 Results of multiple linear regression for log10N2O-N (µg m -2 h -1 ) of urine treated soils at different initial soil pH treatments over time.................................................................60 Table 5-1 Pearson correlation between measured soil variables and NO-N fluxes at day 7..............79 Table 5-2 Pearson correlation between measured soil variables and NO-N fluxes at day 14............79 Table 5-3 Pearson correlation between measured soil variables and NO-N fluxes at day 21............80 Table 5-4 Pearson correlation between measured soil variables and NO-N fluxes at day 28............80 Table 5-5 Pearson correlation between measured soil variables and NO-N fluxes at day 35............81 Table 5-6 Pearson correlation between measured soil variables and NO-N fluxes for data sets pooled over the experimental period. ................................................................................81 Table 5-7 Net NH4 + -N depletion and net NO3 - -N accumulation rates in urine affected soil as influenced by soil temperature (n = 60) and WFPS (n =45) treatments. ...........................85 Table 5-8 Pearson correlation between NH4 + -N:NO3 - -N ratio with soil temperature and WFPS on each sampling date........................................................................................................89 Table 5-9 Mean NO-N flux as a percentage of the mean net NH4 + -N depletion rate at different soil temperatures and WFPS during time periods indicated in paranthesis.....................100 Table 5-10 Pearson correlation between measured soil variables and N2O-N fluxes at day7. ..........106 xi
Page 1 and 2: Factors affecting nitric oxide and
Page 3 and 4: In experiment two (chapter 5) the o
Page 5 and 6: Acknowledgements I am deeply thankf
Page 7 and 8: Table of Contents Abstract.........
Page 9: 6.3.7 NOx fluxes...................
Page 13 and 14: Table 7-1 Mean and S.E.M of soil pH
Page 15 and 16: Figure 4.16 Initial soil pH and NH4
Page 17 and 18: Figure 5.29 Q10(5-15 o C) values fo
Page 19 and 20: Figure 7.13 Soil N2O-N fluxes over
Page 21 and 22: Chapter 1 Introduction Managed past
Page 23 and 24: 2.1 Introduction Chapter 2 Review o
Page 25 and 26: As noted in the introduction N2O is
Page 27 and 28: Figure 2.3 Transformation of minera
Page 29 and 30: 2.5 NOx emissions from urine patche
Page 31 and 32: emissions but not NO. This at odds
Page 33 and 34: 2.6.4 Temperature Soil temperature
Page 35 and 36: 3.1 Introduction Chapter 3 Material
Page 37 and 38: difference. The LMA-3D was also abl
Page 39 and 40: NO 2 reading on LMA-3D (ppbV) 60 50
Page 41 and 42: Concentration (NO-N g m -3 ) 20 18
Page 43 and 44: depth of 7 cm and drying them in th
Page 45: 3.9 Laboratory experiments A Paparu
Page 48 and 49: 4.2 Materials and Methods 4.2.1 Soi
Page 50 and 51: 4.3 Results 4.3.1 Soil NH4 + -N con
Page 52 and 53: NO 2 - -N (g g -1 dry soil) 5 4 3 2
Page 54 and 55: NO x-N Soil pH N 2O-N NH 4 + -N NO
Page 56 and 57: 4.3.3 Soil NO3 - -N concentrations
Page 58 and 59: Table 4-7 Net NH4 + -N depletion an
Page 60 and 61:
4.3.6 Soil surface pH After urine a
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When data were pooled over all samp
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The NO-N flux was influenced by a s
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4.3.8.1 Net NH4 + -N depletion and
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When the mean NO-N flux rate betwee
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4.3.9 N2O fluxes In the absence of
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The cumulative N2O emissions as a p
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µg N 2O-N g -1 soil h -1 0.025 0.0
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concentrations (Tables, 4-2 - 4-5),
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4.4 Regression analysis 4.4.1 Predi
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4.4.2 Prediction of N2O-N When log1
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Soil surface pH increases occurred
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Unlike the NO-N fluxes, which were
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optimum pH was observed for net NO-
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Future work could further examine t
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5.2 Materials and Methods 5.2.1 Tre
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NH 4 + -N (g g -1 dry soil) 1000 80
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NH 4 + -N (g g -1 dry soil) NH 4 +
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NO 2 - -N (g g -1 dry soil) 14 12 1
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NO 2 - -N (g g-1 dry soil) NO 2 - -
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Table 5-3 Pearson correlation betwe
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5.3.3 Soil NO3 - -N concentrations
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NO 3 - -N (g g -1 dry soil) NO 3 -
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Rate of depletion/accumulation (ng
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NH4 + -N:NO 3 - -N ratio 180 160 14
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Surface soil pH 8.0 7.5 7.0 6.5 6.0
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HNO 2 (ng g -1 dry soil) 60 50 40 3
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g NO-N m -2 h -1 140 120 100 80 60
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g NO-N m -2 h -1 50 40 30 20 10 0 2
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Q 10 (15-22 o C) 80 60 40 20 0 11%
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Table 5-9 Mean NO-N flux as a perce
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These treatment effects led to a si
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g N 2O-N m -2 h -1 g N 2 O-N m -2 h
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Temperature Moisture NO-N NH 4 + -N
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Temperature Moisture NO-N NH 4 + -N
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Q 10 (15-22 o C) 100 80 60 40 20 0
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N 2O-N: NO-N 500 400 300 200 100 0
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WFPS (%) 100 80 60 40 20 0 5 10 15
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Table 5-18 The results of multiple
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Table 5-19 The significance of vari
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Table 5-22 The results of multiple
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pool. For example, when averaged ov
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depletion rate, was the soil pH. It
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0.20 g H2O g -1 soil, and temperatu
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the current experimental results. U
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134
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collected from cows at the Lincoln
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NH 4 + -N (g g -1 dry soil) 1200 10
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concentrations increasing at differ
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6.3.4 Net NH4 + -N depletion and NO
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Soil pH 8.0 7.5 7.0 6.5 6.0 5.5 5.0
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6.3.7 NOx fluxes Urine-N applicatio
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Cumulative NO-N (% of urine-N appli
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6.3.7.1 NO-N flux rate as a percent
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6.3.8 N2O fluxes The mean N2O-N flu
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Cumulative N 2 O-N ( % of uine-N ap
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6.3.10 Soil WFPS Soil moisture cont
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Table 6-6 Correlation of log10NO-N
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log 10 NO-N predicted log 10 NO-N p
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6.5 Discussion 6.5.1 Soil inorganic
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The concentrations of HNO2 were thu
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% of NO 2 - -N pool beings turnedov
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6.6 Conclusions Urine-N application
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7.2 Materials and Methods 7.2.1 Fie
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7.2.4 Meteorological data and soil
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7.3.5 Soil ammonium: nitrate ratio
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treatments showed a significant eff
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7.3.7 Theoretical HNO2 concentratio
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7.3.8 Rainfall and Water Filled Por
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7.3.10 NOx fluxes The only gas dete
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7.3.12 N2O-N: NO-N ratio There were
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Table 7-3 Results of multiple regre
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Measured/Predicted NO-N flux 400 30
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The predicted NO-N fluxes were inte
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Table 7-7 Regression coefficients d
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logN 2 O-N 4 3 2 1 0 logN 2 O-N vs
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lowering of the net NH4 + -N deplet
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approximately 6 degrees , NO3 - -N
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204
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8.2 Materials and Method Materials
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8.3.4 Net NH4 + -N depletion rates
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8.3.6 Theoretical HNO2 concentratio
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8.3.8 Soil temperature Mean soil te
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8.3.10 N2O fluxes The N2O-N fluxes
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8.4 Regression analysis 8.4.1 Predi
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The rainfall was regular (after day
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days. This was considerably higher
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to be proportional to the rate of N
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9.7 Future studies The relationshi
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Bronson, K. F., Sparling, G. P., &
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Galbally, I. E. (1989). Factor cont
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Maljanen, M., Martikkala, M., Kopon
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Scholes, M. C., Martin, R., Scholes
Page 256 and 257:
Van Slyke, D. D. (1911). A method f
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