This study compared greenhouse gas emissions from corn and soybean fields under conventional tile drainage (UTD) and controlled tile drainage (CTD) in eastern Ontario, Canada from 2005-2009. Soil methane emissions did not differ between the two drainage treatments. Carbon dioxide emissions were higher under CTD than UTD in 2006 and 2007, and correlated with soil temperature and water table depth. Nitrous oxide emissions did not differ between drainage treatments and correlated most strongly with soil nitrate levels and nitrogen application rate rather than soil water content. The researchers concluded that controlled tile drainage did not significantly increase nitrous oxide or methane emissions during most of the growing season.

1. Measuring the Effects of Water Table
Management On Soil GHG Emissions From
Corn and Soybean Fields In Eastern Canada
V. Nangia1,2, M. Sunohara1, E. Topp1, E. Gregorich1,
C.F. Drury1, N. Gottschall1 and D.R. Lapen1
1Agriculture and Agri-Food Canada
2ICARDA

2. Introduction
2
• Cropping practices affect GHG emissions:
• Crop type/rotation
• Tillage
• Residue management
• Type, timing and method of fertilizer
application
• Modification of soil water status through
irrigation or drainage management also governs
degree of soil GHG emissions

3. Water Table Management
Control
structure
Stop
gate
Conventional Controlled

4. Objective
4
Compare field emissions of soil CH4, N2O, and
CO2 for fields under conventional (UTD) and
controlled tile drainage (CTD) for
corn/soybean cropping system in eastern
Ontario, Canada

5. Site Characteristics
5
• 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

6. Measurement of soil GHG emissions
6
• 2005-2009: Soil GHG measurements from
two field pairs: Field 1 and 2, Field 5 and 6
• In-line control structure closed from planting
to harvest
• GHG chambers installed after planting at 10
cm depth between crop rows (except 2009)
• No. of GHG samples collected:
• CO2: 649
• N2O: 649
• CH4: 617

7. Other measurements
7
• Air temp
• Soil temp
• Precipitation
• Soil-water content (15 cm and 30 cm depth)
• 3 m deep groundwater wells between tiles
• Soil-water content (using TDR) at 30, 60, 90,
120 and 150 cm depths between tiles
• Lysimeters for NO3
- conc. measurement
• Soil sampling for BD, NO3
- and NH4
+

8. Results (Weather and soil conditions)
8
• 2006 (21%) and 2008 (3%) wetter than normal
• 2007 (29%) and 2009 (21%) drier than normal
• Soil temperature did not differ between
treatments
• Average soil water content 1-4% higher in CTD
• Water table depth CTD vs. UTD: p > 0.05
• CTD - greater residence time for GWT depths
< 1m

9. Results (soil CH4 emissions)
9
• Log (CH4): CTD vs. UTD: p > 0.05
• Soils were source of CH4, not a sink
• CH4 emissions higher above tiles compared
to between tiles
• Emissions ranged between 0.0003 and
0.0015 kg C ha-1day-1

10. Results (soil CO2 emissions)
10
• Ranged between 20.4 and 38.9 kg C ha-1
day-1
•Log (CO2): CTD vs. UTD: p < 0.05 in 2006
and 2007 (CTD > UTD)
• CO2 emissions: above vs. between tiles: p >
0.05
• WT depth versus CO2 emissions: p < 0.05
• Soil temp vs. CO2: p < 0.05 (86% times)
• Highest importance (CART analysis): soil
temp, N rate

11. Results (soil N2O emissions)
11
• Ranged between 0.003 and 0.028 kg N ha-1
day-1
•Log (N2O): CTD vs. UTD: p > 0.05
•N2O emission higher between compared to
above tiles
• Highest importance (CART analysis): soil
NO3
-, N application rate, NOT soil-water
content or WT depth

12. Conclusions
12
Water table management does not appear to
be a significant environmental liability with
respect to N2O and CH4 emissions during
majority of the agronomically active season

13. Thank you
V.Nangia@cgiar.org