11th International Drainage Symposium August 30-September 2, 2022 Des Moines, Iowa

1. Long term Benefits of Controlled Drainage
Chandra A. Madramootoo Eng., FASABE
Bioresource Engineering Department
McGill University
Montreal, Canada
September 01, 2022
Des Moines, IA

2. Controlled Drainage
2
Benefits
 Manages the water level and
controls outflow in croplands
 Reduces drainage rates and
volume, making water available to
crops during growing season
 Increases crop yield
 Improves water quality and can
reduce greenhouse gas emissions

3. Study location
3
Location Map of St Emmanuel Field, Southwestern Quebec.

4. Field layout
6
Layout of the experimental plots at St. Emmanuel

5. Study site
5
Parameters QUEBEC
Acreage 4.2 hectares
Soil type Soulanges sandy loam soil of
the Gleysol order
Bulk density 1.36g cm-3
Fertilizer applied 220kg N, 80kg P, 50kg K
Experimental design Randomized complete block
design with repeated measures
Crop yield data 12 years
Water Quality data 7 years
GHG emissions data 6 years

6. Historical corn yield, emissions and
climatic data
Year
Rainfall
(mm)
Temp
(oC)
ETc
Yield
(Mg ha-1)
Difference
in yields
(%)
Mean N2O
fluxes
(mg m-2 hr-1)
CDS TD CDS TD
1993 482 17 421 8.2 8 2.5%
1994 444 17 387 8.9 9.4 -5.3%
1995 479 17 435 11.4 11.1 2.7%
1996 511 17 429 7.3 6.8 7.4%
1998 618 18 449 6.6 8.8 -25.0% 0.041 0.048
1999 482 19 441 9.5 9.7 -2.1% 0.046 0.024
2000 554 16 0.080 0.047
2001 365 18 466 9.4 6.9 36.2%
2002 476 17 483 10.1 7.6 32.9%
2008 433 17 410 12.3 12.5 -1.6%
2009 465 17 407 10.4 11.3 -8.0%
2014 499 18 422 9.7 9.6 1.0% 0.131 0.055
2015 508 19 0.042 0.074
2018 360 19 471 10.9 11 -0.9% 0.025 0.035
8

7. Growing season rainfall distribution
0
50
100
150
200
250
1993
N
1994
D
1995
N
1996
W
1998
W
1999
N
2001
D
2002
N
2008
D
2009
N
2014
N
2018
D
Precipitation
(mm)
May June July August September
Seasonal rainfall distribution for studies that reported grain yields at the study site. N, D,
and W represent normal, relatively dry, and relatively wet years, respectively.
9

8. Corn yields
0
2
4
6
8
10
12
14
1993 1994 1995 1996 1998 1999 2001 2002 2008 2009 2014 2018
Yields
Crop yields (T/ha)
TD CDS
10

9. Effects of CD on crop yields
9
• The test for homogeneity of variances showed there was no significant
difference between CD and TD
• The mean estimate showed there was no significant difference (P>t
=0.664) between CD and TD at the 95% confidence interval.
• CD was positively coefficient to yield by 0.26.
• CD resulted in 3.3% (±16.7%) greater yields than FD over the years at
our site
• The effect of CD on corn yield depended on rainfall distribution and
water table controls during the growing season.

10. Water Quality impacts
10
0
5
10
15
20
25
30
35
1997
1998
1999
2000
2001
2002
2003
NO
3
-N
NO3-N ha yr-1 QC
TD CD

11. Effects of CD on Nitrate
pollution
11
• CD had a significant (P<0.006) effect on leaching with a coefficient of -
17.95675 i.e. CD reduced nitrate leaching over 17 times compared to TD.
• CD combined with Fertilizer had a significant effect (P<0.012) and was
negatively correlated to nitrate leaching,
• Nitrate was negatively correlated to CD (p<0.0018) at 95%.
• The mean values of CD compared TD was P>t=0.0013.

12. Greenhouse gas from CDS vs. TD
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
1998 1999 2000 2014 2015 2018
N
2
O
fluxes
N2O fluxes (mg m-2 hr-1)
TD CDS
14

13. N2O fluxes and rainfall
Figure: N2O fluxes from free drainage (TD) and controlled drainage (CDS)
treatment plots and rainfall amount (mm) over the 2014, 2015 and 2018 growing
seasons.
0
10
20
30
40
50
60
70
80
0.0
0.5
1.0
1.5
2.0
2.5 15-May
30-May
14-Jun
29-Jun
14-Jul
22-Aug
12-Sep
27-Sep
08-May
23-May
07-Jun
22-Jun
23-Jul
07-Aug
22-Aug
06-Sep
21-Sep
11-May
30-May
17-Jun
02-Jul
17-Jul
01-Aug
16-Aug
31-Aug
25-Sep
2014 2015 2018
Precipitation
(mm)
N
2
O-N
flux
(mg
m
-2
hr
-1
)
Precipitation (mm) CDS TD

14. Effects of CD on nitrous oxide
14
• There was no significant effect of CD or TD on N2O emissions at the
95% confidence interval.
• Homogeneity of variances of CD and TD showed no significant
difference (P<0.5355) with mean value of P<0.8483
• The correlation test also showed that both systems had a correlation
coefficient of 0.1427.
• Nitrous oxide fluxes depended more strongly on the availability of soil
nitrogen and rainfall events than the water table treatments

15. Summary
 Controlled drainage is shown to increase corn yields
by 3%, reduces NO3-N pollution and greenhouse gas
emissions (GHG);
 Timing of fertilizer applications and more split
applications could reduce N2O emissions under CD:
 Controlled drainage/subirrigation remains largely
not adopted by growers due to the relatively overall
low increase in crop yields:
 Increased implementation of CD is dependent on
showing the monetized value of environmental co-
benefits of water quality improvement and GHG
reduction.
15

16. Acknowledgements:
• Former and present graduate students, including
Cynthia Creze, Ajay Singh, K. Ekwunife, M. Essein;
• Funding support from NSERC, CFI, AAFC,
McGill University;
• Land owners, Guy and Daniel Vincent