1. Modeling nitrogen gas emission under free and controlled drained at St Emmanuel using Root Zone Water Quality Model
Qianjing Jiang & Zhiming Qi
Department of Bioresource Engineering
McGill University

2. RZWQM2 Algorithm （with DSSAT）
Introduction to RZWQM2
Root Zone Water Quality Model (RZWQM2)
RZWQM2 Algorithm （with DSSAT）
RZWQM2 Interface
（FORTRAN）

3. Components of RZWQM Management effects module
Five highly integrated, but independent, process modules.
Physical processes
(water and chemical transport)
Plant growth processes
Nutrient cycle processes
Pesticide dissipation processes
Equilibrium soil chemistry processes
Management effects module

4. Management Options Planting Fertilizer Applications
Multiple year
Rotation
Fertilizer Applications
Crop specific
BMP driven
Split applications
Pesticide Applications
Microencapsulated
Tillage Operations
Crop Specific
29 different implements
Manure Applications
15 types of Manure
Irrigation and Drainage
Furrow, Sprinkler, or Drip
Automatic irrigation
Control drainage

5. Distinguishing Features of RZWQM2
Agricultural management practices and their effects on crop production and environmental quality ( tillage, irrigation, fertilization, manure application, tile drainage, pesticide application, and crop rotation).
Macropore/preferential flow.
Water table fluctuation and tile flow.
Chemical transport in runoff/percolation water.

6. Distinguishing Features of RZWQM2 (continued)
Detailed plant physiological processes and plant population development (DSSAT crop models).
Detailed carbon/nitrogen dynamics with consideration of microbial populations (OMNI model).
Windows95/98/NT/2000/7 based interface to facilitate data input, analysis, and parameterization.
On-line help to guide model parameterization
Multiple year simulation for crop rotations with capability of answering “what-if” scenarios.

7. Minimum Data Requirements

8. Preliminary Test on Root Zone Water Quality Model
Simulating period: 2011/10/ /8/13
Water table management:
Free drainage
Controlled drainage (headgate set at 60 cm from May 21st to Sept 15th each year)
Location:St Emmanuel, 60 km west of Montreal, Southern Quebec, Canada

9. Site Description
Free Drainage depth: 1.0 m Controlled Drainage with Subirrigation: m May to Sep
Simulation period: /10/ /8/13escription
0-25 cm sandy loam
25-55 cm sandy clay
cm clay
Low N: 120 kg N/ha
Medium N: 180 kg N/ha
High N: 260 kg N/ha
Continuous Corn

10. Crop & Soil information
Crop: Corn
Planting date: May 4th,
Row spacing: 76 cm; Planting depth: 4cm
Planting density: seeds/ha
Harvest date: October 25th,
N application
2012
2013
2014
2015
2-May 88 52
5-May 24
167
17-Jun
122
Total N
234
219
Soil properties
Texture
% Clay
% Silt
% Sand BD pH OM
Depth
Mg m-3 %
0-20 cm
Sandy clay loam
31.99
19.23
48.78
1.4
6.7
3.98
20-40 cm
Sandy loam
16.7
31.95
51.35
1.5
3.01
40-60 cm
14.83
24.82
61.05
6.8
2.06
60-80 cm
Clay loam
32.4
22.14
45.47
1.3
7.0
2.15

11. Calibrated soil hydraulic parameters
Layer
Depth
(cm) BD
(Mg m-3)
Soil Water Retention
Lateral KSAT
(cm h-1)
KSAT θs
(cm3cm-3) θr τb λ
SRGF 1
0-15
1.4
0.452
0.075
-10.0
0.234
5.0
3.0
1.0 2
15-35
1.5
0.424
0.071
-18.0
0.224 3
35-45
0.400
0.041
0.232
0.30 4
45-80
1.3
0.460
-15.6
0.320
12.0
6.0
0.07 5
80-120
0.464
0.304
2.0 6
0.23
0.01 7 8 9 10
0.1
After a lot of trials, I got some results for the paramters. And here are the soil hydraulic parameters been calibrated to simulate the soil water condition based on the measurement of soil profile, soil texture and soil moisture content.
BD = bulk density, θs = saturated soil water content, θr = residual soil water content, τb = bubbling pressure, λ = pore size distribution index, KSAT =saturated hydraulic conductivity; SRGF = soil root growth factor.
BEA Confidential

12. Preliminary Results
FD, free drainage; NxO, all nitrogen gas except for N2O
Pearson Correlation between rainfall and N2O: 0.415

14. NxO: Other Nitrogen Oxides except N2O
Rain
(cm)
Tile Drainage (cm)
CO2 Release (kg-C/ha)
N2O Emission (kg-N/ha)
NxO Emission (kg-N/ha)
Denitrification (kg-N/ha)
Sum
N2O Emission from nitrification
(kg-N/ha) FD CD
2011(67)
10.2
3.1
644.7
3.4
1.4
3.9
3.0
2012(365)
100.0
26.3
24.7
4963.3
4701.8
19.9
20.1
8.7
2.1
2.4
19.8
20.0
2013(364)
94.8
10.9
9.6
6004.9
5770.1
4.9
4.8
2.3
2.2
0.5
0.6
2014(364)
108.5
8.5
8.2
5865.5
5746.4
5.9
4.0
2015(223)
57.5
6.5
3.7
3341.0
3243.2
1.2
0.4
sum
371.0
55.3
49.3
36.4
19.1
17.5
7.3
7.8
35.9
(CD-FD)/FD
-10.8%
-3.4%
0.0%
-8.3%
5.7%
NxO: Other Nitrogen Oxides except N2O

17. Soil water content in the top layer (0-15 cm) & N2O emission (FD)

18. Soil Temperature at surface (0-15cm) & N2O emission(FD)

19. Preliminary Conclusion
N2O is affected by rainfall
N2O is not very relevant with soil temperature
N2O is closely related to fertilizer application
Control drainage does not increase nitrogen gas emission.