1. Assessing Field-Scale Effects of Controlled Tile
Drainage On N Mass Balance From Corn and
Soybean Fields In Eastern Ontario, Canada
V. Nangia1,2, M. Sunohara1, E. Topp1, N. Gottschall1,
C.F. Drury1, M.A. Youssef and D.R. Lapen1
1Agriculture and Agri-Food Canada
2ICARDA

2. Introduction
2
• N budgets help understand NUE and ways to
mitigate water, air and soil contamination
•Controlled tile drainage regulates amount of
water that can leave a field

3. Controlled Tile Drainage
Control
structure
Stop
gate
Conventional Controlled

4. Advantages of CTD
4
• Manipulates WT elevation and soil-water
content
• Allows crops to more readily access water
and nutrients
• Reduces net export of nutrients and other
agriculturally-derived contaminants

5. Objective
5
To measure and estimate major N inputs and
outputs during the growing season for eight
(four pairs) extensively tile-drained agricultural
fields under maize/soybean production system
to contrast between controlled and
uncontrolled tile drainage management
practice

6. Site Characteristics
6
• Site situated within ~950 ha experimental
watershed in eastern Ontario
• 30-year mean yearly rainfall: 944 mm
• Mean annual min/max temp: 1.1oC / 10.9oC
• Silt loams are dominant soils at the fields
• < 1% surface slope
• Tile drainage: 1 m deep; 17 m apart; 0.1%
slope

7. Methodology
7
• Conducted study on four pairs (eight fields) of
comparable size, soil type and cropping mgmt.
• From 2005-2009 (Apr-Oct), measured and
estimated major N inputs and outputs for CTD
and UTD fields
• Predicted N emissions using the NEMIS-NOE
model:
N2O: ƒ(soil temp, soil-water content, soil NO3
-)

8. N Inputs
8
• Inorganic N or N fixation
• Wet and dry deposition
• Spring soil N
• Spring GW N

9. N Outputs
9
• In field
• NO3-N
• NH4-N
• Edge of Field
• Plant N uptake
• N2O-N
• N2-N
• Fall soil N
• Fall GW N
• Groundwater vertical
• NO3-N
• NH4-N
• Groundwater lateral
• NO3-N
• NH4-N

10. Cropping Practice
Fields 2006 2007 2008 2009
1, 2 Corn Corn Soybean Corn
3, 4 Corn Corn Soybean
5, 6 Soybean Corn Corn
7, 8 Corn Corn Soybean
10

11. Results
11
• 2006 (21%) and 2008 (3%) wetter than normal
• 2007 (29%) and 2009 (21%) drier than normal
• CTD Corn yields higher by 4% (p = 0.58)
• CTD Soybean yields higher by 3% (p = 0.08)
• Leading to 3% higher N uptake in CTD-
managed fields

12. Results
12
• 52% reduction in tile discharge
• 47% reduction in tile drain N losses
• 17% higher predicted N emissions
(nitrification + denitrification) than UTD
• Vertical deep seepage: 0.0 to 1.9 kg N ha-1
(CTD > UTD)

13. Results
13
∆inputs – ∆outputs – ∆soil residue N = Residual
• Residuals ranged between -67 and 26 kg N ha-1

14. Thank you
V.Nangia@cgiar.org