High Tunnel irrigation overview presented by University of Minnesota retired Extension Engineer, Jerry Wright at the 2009 Minnesota Statewide High Tunnel Conference in Alexandria, MN on Dec. 2-3, 2009.

1. Irrigation Concerns
within
High Tunnel Production Systems
Jerry Wright, Retired Extension Engineer
University of Minnesota Extension
Bioproducts & Biosystems Engineering Dept
West Central Research & Outreach Center - Morris, MN
High Tunnel Workshop – December 2, 2009
jwright@umn.edu
Making a Difference in Minnesota
© 2009 Regents of the University of Minnesota

2. Uniformity of
Irrigation Water
Application
• Irrigation Water Quality
– Sedimentation, algae
– Water chemistry – salinity,
calcium, iron, pH
• Adequate filters after water
source and fertigation system
• Water Compatibility
with fertilizer Making a Difference in Minnesota
Jerry Wright, University of Minneota
Extension
© 2009 Regents of the University of Minnesota

3. Uniformity of Water
Application
• Adequate filters after water
source and fertigation system
• Check Water Compatibility with
fertilizer!!!!! - 2009 Crookston
Making a Difference in Minnesota
Jerry Wright, University of Minneota
Extension
© 2009 Regents of the University of Minnesota

4. Drip Irrigation Control Assembly
Making a Difference in Minnesota
Jerry Wright, University of Minneota
Extension
© 2009 Regents of the University of Minnesota

5. Routine Line & Filter Flushing
Making a Difference in Minnesota
Jerry Wright, University of Minneota
Extension
© 2009 Regents of the University of Minnesota

6. Uniformity of Irrigation Water
Application
• Water Pressure Distribution
– Along header & lateral lines
• Adequate pipeline diameter to
minimize friction losses
• Friction loss through filters,
controllers and fertigation valves
• Pressure Regulator & Gages
Making a Difference in Minnesota
Jerry Wright, University of Minneota
Extension
© 2009 Regents of the University of Minnesota

7. When & How Much Should I Water????
Jerry Wright, University of
© 2009 Regents of the University of
Minneota Extension Minnesota

8. High Tunnel - Soil & Plant
Water Management
• Irrigation timing and application depth
– Over watering leaches nutrients & reduces O2
– Under watering affects fruit growth & quality
• Know your systems application rate
– Gallons per linear foot per hour
– Inches of water depth per hour
Making a Difference in Minnesota
Jerry Wright, University of Minneota
Extension
© 2009 Regents of the University of Minnesota

9. Drip Irrigation System
Water application rate!!!
Table 4: Average Application Rate from Drip Irrigation Systems
by Jerry Wright, Extension Engineer, University of Minnesota
Email: jwright@umn.edu (April 2005)
Drip Tube Flow ********** Wetted Soil Width in Inches *************
GPM GPH 8 12 16 20 24
per 100ft per 100ft Average Application Rate - Inches per Hour
0.200 12 0.29 0.19 0.14 0.12 0.10
0.250 15 0.36 0.24 0.18 0.14 0.12
0.300 18 0.43 0.29 0.22 0.17 0.14
0.350 21 0.51 0.34 0.25 0.20 0.17
0.450 27 0.65 0.43 0.32 0.26 0.22
0.670 40 0.97 0.64 0.48 0.39 0.32
0.850 51 1.23 0.82 0.61 0.49 0.41
1.700 102 2.45 1.64 1.23 0.98 0.82
Appl. Rate inches/hour = 12 in/ft * (GPH/100ft)/(7.48 gal/cuft * 100 * wetted width in feet)
file: irrigation gallons per ET version 3e.xls
Jerry Wright, University of
© 2009 Regents of the University of
Minneota Extension Minnesota

10. High Tunnel - Soil & Plant
Water Management
• Know the soil texture and drip
irrigation water movement
– wetted soil pattern - width & depth
– May need more than one drip line per row/bed
• Understand plants water needs:
– Increases with Plant density and foliage size
• Daily crop ET (.1 to .25 inches per day)
– .3 to .7 gallons per plant per day (research very limited)
• Different crops may need difference irrigation schedules
– Install small control valve on each irrigated row
– Plant same crop type and planting date in same row
Making a Difference in Minnesota
Jerry Wright, University of Minneota
Extension
© 2009 Regents of the University of Minnesota

11. Average Irrigation Applied in High Tunnel Tomatoes
Gallons per Plant per inDay - Tomatoes
Average Irrigation Applied High Tunnel
Staples 2005
field observations Gallons per Plant per Day - Staples 2005 use more water
indicate cucumbers can
1.00
Plt/dy in 18" spacing Plt/dy in 24" spacing
0.90
Poly. (Plt/dy in 18" spacing) Poly. (Plt/dy in 24" spacing)
0.80
0.70
Gallons per Plant per da
0.60
0.50
0.40
0.30
0.20
0.10 Making a Difference in Minnesota
0.00
3-Jul
10-Jul
17-Jul
24-Jul
31-Jul
5-Jun
12-Jun
19-Jun
26-Jun
2-Oct
9-Oct
15-May
22-May
29-May
4-Sep
11-Sep
18-Sep
25-Sep
7-Aug
14-Aug
21-Aug
Jerry Wright, University of Minneota 28-Aug
Extension
© 2009 Regents of the University of Minnesota

12. In-Field Soil Water Assessment
Making a Difference in Minnesota
Jerry Wright, University of Minneota
Extension
© 2009 Regents of the University of Minnesota

13. SOIL WATER DEFICITS
for
Typical Soils & Soil Water Tensions
Good Range for High Tunnels - 25 to 40 centibars
Soil water tension in centibars, cbs
Soil Texture
10 30 50 70 100 200 1500**
Soil water deficit – inches per foot of soil
Coarse sand 0 0.1 0.2 0.3 0.4 0.6 0.7
Fine sand 0 0.3 0.4 0.6 0.7 0.9 1.1
Loamy sand 0 0.4 0.5 0.8 0.9 1.1 1.4
Sandy loam 0 0.5 0.7 0.9 1.0 1.3 1.7
Loam 0 0.2 0.5 0.8 1.0 1.6 2.4
**1500 cbs is approximately the permanent wilting point for most plants and the
soil water deficit values equal the soil’s available water holding capacity
Jerry Wright, University of
© 2009 Regents of the University of
Minneota Extension Minnesota

14. Soil Water Monitoring Sensors
Jerry Wright, University of
© 2009 Regents of the University of
Minneota Extension Minnesota

15. Soil Water Monitoring
Irrometer Co - http://www.irrometer.com/
Jerry Wright, University of
Spectrum2009
© Technologies http://www.specmeters.com
Regents of the .University of
Minnesota
Minneota Extension
-

16. High Tunnel - Soil & Plant
Water Management
• Automation of irrigation system
– Manual On switch with timer shut-off
• Good for small - low flow systems
• Too much pressure loss for high flow rates
– Full timer 7day – 24 hour control
• Can control one valve or multiple valves
• Many sizes available & low friction loss
Making a Difference in Minnesota
Jerry Wright, University of Minneota
Extension
© 2009 Regents of the University of Minnesota

17. Automatic Controllers
Jerry Wright, University of
© 2009 Regents of the University of
Minneota Extension Minnesota

18. Failed Irrigation with Automatic Timer
Jerry Wright, University of
© 2009 Regents of the University of
Minneota Extension Minnesota

19. Closing Comments
• Know your irrigation system
• Learn how water moves in your soil
• Do not over irrigate!!!!
• Automation & Fertigation requires a
watchful eye !!!!
Making a Difference in Minnesota
Jerry Wright, University of Minneota
Extension
© 2009 Regents of the University of Minnesota