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

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

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

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

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.

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.

Minimum Data Requirements

Preliminary Test on Root Zone Water Quality Model Simulating period: 2011/10/26-2015/8/13 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

Site Description Free Drainage depth: 1.0 m Controlled Drainage with Subirrigation: 0.6m May to Sep Simulation period: 2011/10/26-2015/8/13escription 0-25 cm sandy loam 25-55 cm sandy clay 55-100 cm clay Low N: 120 kg N/ha Medium N: 180 kg N/ha High N: 260 kg N/ha Continuous Corn

Crop & Soil information Crop: Corn Planting date: May 4th, 2012-2015 Row spacing: 76 cm; Planting depth: 4cm Planting density: 89000 seeds/ha Harvest date: October 25th, 2012-2014 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

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 6 120-170 0.23 0.01 7 170-230 8 230-300 9 300-380 10 380-397 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

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

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 20819.4 20106.2 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

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

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

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.