This study compared the effects of controlled drainage and subirrigation (irrigation) to conventional drainage on a field site in Finland. Measurements showed that controlled drainage maintained higher groundwater levels. Yield was slightly higher under controlled drainage. Nutrient loads (nitrogen and phosphorus) and suspended solids in drainage water were generally lower under controlled drainage, especially when irrigation was removed. The conclusions were that controlled drainage can benefit water management when combined carefully with low-intensity subirrigation to avoid increasing nutrient loads.

1. International Drainage
Symposium
September 1st 2022
Des Moines, Iowa
Agricultural water management with
controlled drainage and subirrigation
- results from a Nordic field in level
terrain
Minna Mäkelä1, Helena Äijö1, Markus Sikkilä5, Jyrki Nurminen4,
Heidi Salo3, Aleksi Salla3; Merja Myllys2, Harri Koivusalo3
1Finnish Field Drainage Association
2Natural Resources Institute Finland
3Aalto University, Department of Built Environment
4Field Drainage Research Association,
5Maveplan Oy

2. VesiHave and Vesihave2- projects
 Partners: Finnish Field Drainage Association, Natural Resources
Institute Finland, Field Drainage Research Association, Aalto
University, Sven Hallin Research Foundation sr,
 Funding: Ministry of Agriculture and Forestry of Finland, Ministry
of the Environment, Drainage Foundation sr, Maa- ja vesitekniikan
tuki ry, partners
 Total duration 2019-2022
 Results presented from 2019-2021

3.  To produce information to be used in agricultural water
management planning, so that nutrient loading may be
minimised, while soil structure and fertility are maintained
 Several work packages including supplementary drainage, main ditch
damming and modelling
 Experiment in Sievi: To find out the effects of controlled
drainage and subirrigation have on field productivity and
environmental load.
Objective of the project

4. Reseach site: Agricultural
field in Sievi, Finland
• Texture varies between loam
and sandy loam
• Endogleyic Umbrisol
according to the WRB system
• Slope less than 0.2 %
• Cultivated on a rotation of
cereal crops and grass
• Subsurface drainage installed
in 2015, before that open
ditches
• In research use since 2015, in
co-operation with FIDAS

6. • 2 plots
• Controlled
Conventional
• 12 drains per plot
• Separate collectors
• Controlled plot
isolated with a plastic
sheet
Drainage map
• Measurements
• Groundwater level
- by hand at 56 spots
- automatically at locations 2&6
• Drainage discharge at the
instrument well
• Soil moisture, starting in 2021
• Yield
• Drainage water quality
• Flow weighted sampling
Subirrigation
• In 2019-2020 a combustion engine
powered pump: very efficient but
labor intensive to maintain
• In 2021 a solar powered pump: less
powerful but almost free of
maintenance

7.  Ultrasound flow measurement
 Water quality sampling
 Aggregate sample taken relative to discharge
 Magnetic valve+logger
Measurements on drainage discharge
Contol well
Inspection
well
Instrument well
Instrument well
Logger

8. • Four replicates at different distance from drain:
0.2, 0.6, 2.5, 7.5 m
• By hand 2 x 28 kpl
• 2 automatic measuring stations (2 x 4)
Groundwater measurement
0
50
100
150
200
-8.0 -3.0 2.0 7.0
12.1.2020 4.2.2020 29.5.2020
13.7.2020 8.8.2020 24.11.2020

10. Groundwater
level

11. 0
5
10
15
20
25
30
0
0.5
1
1.5
2
2.5
14/4/2021 14/5/2021 13/6/2021 13/7/2021 12/8/2021 11/9/2021 11/10/2021 10/11/2021 10/12/2021 9/1/2022 8/2/2022 10/3/2022 9/4/2022 9/5/2022 8/6/2022 8/7/2022 7/8/2022
Sadanta
(mm)
Pohjaveden
pinta
(m)
Sievi Groundwater Level, 0,2 m from Drain
Convention
al 0,2 m
Controlled
0,2 m
0
5
10
15
20
25
30
0
0.5
1
1.5
2
2.5
14/4/2021 14/5/2021 13/6/2021 13/7/2021 12/8/2021 11/9/2021 11/10/2021 10/11/2021 10/12/2021 9/1/2022 8/2/2022 10/3/2022 9/4/2022 9/5/2022 8/6/2022 8/7/2022 7/8/2022
Sadanta
(mm)
Pohjaveden
pinta
(m)
Sievi Groundwater Level, 0,6 m from Drain
Controlled
0,6 m
Conventiona
l 0,6 m

12. 0
5
10
15
20
25
30
0
0.5
1
1.5
2
2.5
14/4/2021 14/5/2021 13/6/2021 13/7/2021 12/8/2021 11/9/2021 11/10/2021 10/11/2021 10/12/2021 9/1/2022 8/2/2022 10/3/2022 9/4/2022 9/5/2022 8/6/2022 8/7/2022 7/8/2022
Sadanta
(mm)
Pohjaveden
pinta
(m)
Sievi Groundwater Level, 2,5 m from Drain
Controlled
2.5 m
Convention
al 2.5 m
0
5
10
15
20
25
30
0
0.5
1
1.5
2
2.5
14/4/2021 14/5/2021 13/6/2021 13/7/2021 12/8/2021 11/9/2021 11/10/2021 10/11/2021 10/12/2021 9/1/2022 8/2/2022 10/3/2022 9/4/2022 9/5/2022 8/6/2022 8/7/2022 7/8/2022
Sademäärä
(mm)
Pohjaveden
pinta
(m)
Sievi Groundwater Level, 7,5 m from Drain
Controlled
7.5 m
Convention
al 7.5 m

13. Drain discharge Annual discharge, mm
Control with
irrigation
Control without
irrigation Conventional
2020 672 359 410
2021 259 233 355
0
200
400
600
800
1000
1200
0
5
10
15
20
25
30
January-19 April-19 July-19 October-19 January-20 April-20 July-20 October-20 January-21 April-21 July-21 October-21
Cumulative
(mm)
mm
d
-1
Controlled Conventional Controlled cumulative Conventional cumulative
Irrigation
Damming on
3.6.2019
Irrigation
Irrigation
Irrigation
0
200
400
600
800
1000
1200
0
5
10
15
20
25
30
January-19 April-19 July-19 October-19 January-20 April-20 July-20 October-20 January-21 April-21 July-21 October-21
Cumulative
(mm)
mm
d
-1
Controlled, irrigation removed Conventional Controlled cumulative, irrigation removed Conventional cumulative
Damming on
3.6.2019

14. Soil moisture
0
10
20
30
40
50
60
6/10/2021 7/10/2021 8/9/2021 9/8/2021 10/8/2021 11/7/2021
%
Sievi, maan kosteus, syvyys 15 cm Säätö_15_1 Säätö_15_2 Verrokki_15_1 Verrokki_15_2
0
10
20
30
40
50
60
6/10/2021 7/10/2021 8/9/2021 9/8/2021 10/8/2021 11/7/2021
Kosteus
%
Sievi, maan kosteus, syvyys 70 cm Säätö_70_1 Säätö_70_2 Verrokki_70_1 Verrokki_70_2

15. Yield
 Slightly higher with controlled
drainage (2-6 %), large variation
0
2000
4000
6000
8000
10000
12000
2019: Rye, kg/ha
Säätö Tavanomainen
0
1000
2000
3000
4000
5000
6000
2020: Barley kg/ha
Säätö Tavanomainen
0.00
10000.00
20000.00
30000.00
40000.00
50000.00
60000.00
2021: Grass biomass, kg/ha
säätö Tavanomainen

16. Greenhouse gas emissions
 Sampled with the static chamber method in
four replicates
 Four sampling events in 2020 and five in 2021
 No systematic differrence between plots
Annual emission Controlled Conventional
CO2 , g m
-2
a
-1
2260±280 2510±309
CH₄ , g m
-2
a
-1
0.074±0.048 -0.006±0.064
N₂O , g m
-2
a
-1
0.066±0.008 0.14±0.069
0
50
100
150
200
250
0
0.2
0.4
0.6
0.8
1
1.2
May
15,2020
Sep
14,2020
Sep
28,2020
Oct
14,2020
May
11,2021
May
27,2021
Aug
27,2021
Oct
14,2021
Nov
19,2021
Groundwater
evel,
cm
CO2,
g/m2/h
CO2 emission
Controlled Conventional Grounwater level, Controlled Groundwater level, Conventional
0
50
100
150
200
250
0
0.00002
0.00004
0.00006
0.00008
0.0001
0.00012
May
15,2020
Sep
14,2020
Sep
28,2020
Oct
14,2020
May
11,2021
May
27,2021
Aug
27,2021
Oct
14,2021
Nov
19,2021
Groundwater
evel,
cm
N2O,
g/m2/h
N2O emission
Controlled Conventional Grounwater level, Controlled Groundwater level, Conventional

17. Water quality, aggregate samples
 Total P concentrations vary
between 0,01-0,086 mg/l
 Higher concentrations in the
controlled plot in autumn
2020
 Total N
 Varies between <1-30 mg/l
 Lower concentrations at the
control plot
 Suspendedn solids (GF/C)
quite low
 Less than 30 mg/l

18. Water Quality: Nitrogen
 Total N smaller
in Controlled
drainage since
autumn 2020
0
5
10
15
20
25
30
35
mg/l
Tot-N concentration Säätö Verrokki
0
20
40
60
80
100
11/1/2019 2/9/2020 5/19/20208/27/202012/5/20203/15/20216/23/202110/1/2021
kg/ha
Sievi, Tot-N -load
Säätö Verrokki
0
20
40
60
80
100
11/1/2019 2/9/2020 5/19/2020 8/27/2020 12/5/2020 3/15/2021 6/23/2021 10/1/2021
kg/ha
Sievi, Tot-N -load, irrigation removed
Säätö Verrokki

19. Water Quality:Phosphorus  Total P
concentration
variable
 Higher in
controlled
drainage in
autumn 2020
0.00
0.02
0.04
0.06
0.08
0.10
mg/l
KOK-P -pitoisuus Säätö Verrokki
0.00
0.10
0.20
0.30
0.40
Oct-19 Jan-20 Apr-20 Jul-20 Nov-20 Feb-21 May-21 Aug-21
kg/ha
Sievi, Tot-P -load
Säätö Verrokki
0.00
0.05
0.10
0.15
0.20
Oct-19 Jan-20 Apr-20 Jul-20 Nov-20 Feb-21 May-21 Aug-21
kg/ha
Sievi, Tot-P -load
Säätö Verrokki

20. Suspended solids
0
10
20
30
40
50
60
mg/l
Suspended solids (GF/C) Säätö Verrokki
0
50
100
150
200
250
300
350
Oct-19 Jan-20 Apr-20 Jul-20 Nov-20 Feb-21 May-21 Aug-21
kg/ha
Sievi, Suspended solids
Säätö Verrokki
0
50
100
150
200
Oct-19 Jan-20 Apr-20 Jul-20 Nov-20 Feb-21 May-21 Aug-21
kg/ha
Sievi, Suspended solids
Säätö Verrokki

21. Conclusions
 Controlled drainage combined with subirrigation can be used to
maintain a higher groundwater level.
 Measures should be started early, before groundwater level recedes too
much.
 Irrigation should be at a low intensity, to allow water to infiltrate into the soil
and to avoid incresed discharge.
 Controlled drainage alone diminishes nutrient load and erosion, but
excessive irrigation will cause increased load.