1. Managing Irrigation water:
Lyndon Kelley
MSU Extension / Purdue University Irrigation Management Agent
- find St. Joseph Co.
- then hit the Irrigation button

2. Size , Scale and Make-up Indiana 313,000 acres
Michigan – 452,000 acres
County
Irrigated Acres %
LaPorte
32,400
10.4
Knox
24,600
7.8
Elkhart
23,500
7.5
LaGrange
21,700
6.9
Jasper
20,600
6.6
St. Joseph
19,500
6.2
Pulaski
19,200
6.1
Kosciusko
19,100
Fulton
16,200
5.2
Starke
11,100
3.5
Bartholomew
9,100
2.9
County
Irrigated Acres %
St Joseph
104,000
23.0
Montcalm
47,000
10.4
Branch
39,300
8.7
Kalamazoo
29,600
6.6
Cass
25,400
5.6
Van Buren
23,900
5.3
Berrien
19,200
4.2
Allegan
15,300
3.4
Ottawa
13,500
3.0
Calhoun
10,400
2.3
Tuscola
5,800
1.3
Summarized from 2002 Agricultural Census
11 Counties = 73.8 % of total
11 Counties = 69.2 % of total

3. Needed Irrigation
5.5”
Normal rainfall
34.6
Crop need
15.6” total

4. Estimated rainfall recharge
Scientific Investigations Report 2005–5284
U.S. Department of the Interior
U.S. Geological Survey

5. Water Quantity Needed
Irrigation water replaces the plant water use (removed from soil)
Water use is directly correlated to light interception
50% light interception results in about 50% of the maximum water use
Maximum water use mid-July early August, full light interception, highest temperatures brightest and longest days.
Evapotranspiration (ET) = fn (net radiation) +
fn (temperature) +
fn (wind speed) +
fn (air humidity)

6. Weighing Lysimeter Rain and Irrigation increase weight
Evapotransporation decrease weight

7. Soys Potato Alfalfa Alfalfa Soys Corn Field beans Corn Field beans
From Minnesota Extension bulletin “Irrigation Scheduling”, assuming temperature 80-89

12. Three factor reducing effective water application
2. Lack of system uniformity
5-35% loss in effectiveness
Three factor reducing effective water application
Sprinkler overlap with end gun
1. Irrigation Runoff (comparing irrigation application rate to soil infiltration rate) % loss
3. Evaporative loss to the air
Minimal loss in our humid area
0 – 6%
Estimated 4-6% loss in Nebraska

13. Average application efficiency Desired Inches of effective application
Necessary application rate to achieve effective
evapo-transportation rates at various application efficiencies
Average application efficiency
Desired Inches of effective application
70%
75%
80%
85%
90%
95%
0.16
0.21
0.20
0.19
0.18
0.17
0.23
0.22
0.26
0.25
0.24
0.29
0.28
0.31
0.30
0.34
0.33
0.27
0.36
0.35
0.32
0.39
0.38
0.42
0.40
0.37

14. Quantity Needed Maximum water use for most crops is .27 - .32 in./day
3 gal/minute/acre pump capacity = 1”/week
5 gal/minute/acre pump capacity = .25 in./day
7 gal/minute/acre pump capacity =.33 in./day, 1”every 3 days
500 gal/minute pump can provide 1” every 4 days on 100 acres

15. Think of your soil as a bank
Soil type :
Heavier soil can hold more water / foot of depth than light soils
Water holding capacity:
The soil (bank) can hold only a given volume of water before it allow it to pass lower down.
Intake rate:
Water applied faster than the soil intake rate is lost.
Deletion:
Plants can pull out only % of the water
Rooting depth:
The plant can only get water to the depth of it’s roots.
Water lost from the bottom of the profile can wash out (leach) water soluble nutrients and pesticides.

16. Calculating Water Holding Capacity
Soil Name
Depth
Inches
Available water holding capacity
Average Available water holding capacity
Ave. Available water holding capacity
( 24 in.)
( 36 in.)
Oshtemo
0 - 14
14 – 35
0.10 – 0.15
0.12 – 0.19
0.06 – 0.10
0.125
0.155
0.08
14” x 0.125=1.75
10” x 0.155=1.55
= 3.3
14” x 0.125= 1.75
21” x 0.155= 3.26
1” x = 0.08
= 5.09
Spinks
0 – 10
10 – 26
0.08 – 0.10
0.04 – 0.08
0.09
0.06
10” x 0.09= 0.9
14” x 0.09= 1.26
= 2.16
16” x 0.09= 1.26
8” x 0.06= 0.48
= 2.64

17. Calculating drought capacity
Crop ET. was 0.30 in./day
Available water capacity of 03.0 in. (AWCI
Irrigation system can apply 0.20 in./day.
Started irrigating when the AWC was 1.0 in. down
3.0 in. (AWC) in. = 2.0 in. available capacity
2.0 in. available capacity / 0.10 daily deficit = 20 days
20 days of drought capacity- Not Considering down time

18. Limited water supply Irrigation Management
Diversify the crops sharing the water supply between high and low water use.
Stager planting date to stager peak water need times.
Plant part of irrigated area to a sacrifice crop to neglect during extended drought.
Start irrigating early to bank water ahead.
Stager forage crop cutting dates to avoid simultaneous peak use.

19. 20 acres
30 acres
20 acres
30 acres
1320’
Field #10
1109’

20. SW 1/4
6-1-08
corn
3.0
36” 50
1.5
Available
2.00
1.85
1.70
1.52
1.34
1.94
1.79
Jun 21
Jun 22
Jun 23
Jun 24
Jun 25
Jun 26 75 85
.15
.18
-0-
0.75

21. Mendon Estimated Evapotranspiration (ET) for July 4, 2008
Irrigation scheduling links:
Historical E.T. for this site
MSU Scheduler IS 4
MichIana Irrigation Scheduler
MSU Scheduler Excel
MSU Paper check book system
Explanation of estimated E.T..
Corn – 105 day maturity emerging on the listed date in 30” rows.
Soybean – for grow 3.0 emerging on the listed date.
E.T. have been estimate for two days in the future based on future weather forecast.
Date-
July 1
Stage/
ET.Estimate
July 2
Stage/ ET.Estimate
July 3
July 4
July 5
July 6
Corn
Emerged
May 1
.19
1st. Tassel
.20
full tassel
.22
May 7
.17
10 leaf
May 14
.15
8 leaf
.16
Soybean
6th. Trifolliate
.18
First flower
.21
4th. Trifolliate
Grass -reference crop
4” standard
4” standard .20
4” standard .17

23. MichIana Irrigation Scheduler: Purdue Agronomy web site
–Est. From High / Low temp. & date

26. MichIana Irrigation Scheduler – out put

27. Irrigation Scheduling Checkbook Challenges
?? Soil Moisture ??
Errors will accumulate over time -Weekly ground truthing needed
Rainfall variability is more than often considered
Only "effective” rainfall and irrigation should be considered - Only water entering root zone uniformly is "effective”
Corn crop mature in program by calendar, not heat

28. Methods to Estimate Soil Moisture
Feel an Appearance
Electrical resistance – electrodes on blocks in soil
Tensiometers – measures soil moisture tension

34. Qualitative evaluation of soil water monitoring devices.
DEVICE NP
TDR GS AP AQ TM GB WB
INITIAL COST 3 1 8 2 7
FIELD SITE SETUP REQUIREMENTS 10 6
OBTAINING A ROUTINE READING 4
INTERPRETATION OF READINGS 5
ACCURACY
MAINTENANCE 9
SPECIAL CONSIDERATIONS
COMPOSITE RATING 49 52 48 42 47 41
A score of 1 is least favorable while a score of 10 is most favorable.
NP - Neutron Probe
TDR -Time Domain Reflectometry
GS - Gravimetric Sampling
AP - Troxler Sentry 200-AP
AQ - Aquaterr Probe
TM - Tensiometer
GB - Gypsum Block
WB - Watermark Block

35. Gravimetric Sampling Wet weight – Dry weight of a know volume of soil.
Often refered to as a “can test”

36. Have you seen yield map patterns that match the irrigation system configuration?

37. Sprinkler overlap with end gun
Joe /Irrigation
Sprinkler overlap with end gun
Tower 1
Tower 3
Tower 5
Tower 7
Tower 8

38. Greatest improvement needed
End gun stop adjustment
Water supply over or under design
End gun orifice, too little or too much
Wrong sprinkler or tip
Leaks, plugs and no turn sprinklers

39. Water supply over or under design supply over design yield tail up, supply under design yield tail down Example of Water supply under volume for sprinkler design

40. 330’
495’
660’
990’
2 acres
18 acres
31 acres
49 acres
71 acres
96 acres
126acres
10 acres
13 acres
22 acres
25 acres
30 acres
Total Acres
4145’
3109’
2072’
5181’
6217’
7253’
8290’
circumference
Over and under application issue affect the majority of the application area
8 acres
6 acres
165’
825’
1155’
1320’
Feet from center

41. Most system apply within 85% of the expected application
Application is 4 %
under expectation

42. Measure flow at desired pressure prior to ordering sprinkler package
Poor performance:
Ask dealer to measure flow at peak water use season and compare to design parameters.

43. Assure the best plant stand possible
Irrigate, if necessary, to make sure to get maximum germination and uniform emergence.
Wet down 2.5” within five days of planting, ½” in most irrigated soil
Maintain a moist surface,0.10” to 0.20” applications, till spike.
Are you ready to irrigate the day you plant?

44. Using irrigation to get the most from pesticides and nutrients
Timely application of irrigation water:
Improves incorporation of herbicides.
Improves activation of herbicides.
Improves activation/reactivation of insecticides.
Reduces nitrogen volatilization.
Maximizes yield to utilize the resources.

45. Do not apply this product through any type of irrigation system.
If available, sprinkler irrigate within 2 days after application. Apply ½” -1” of water. Use lower water volumes (½” ) on coarse-textured soils, higher volumes heavier soils (1”) on fine-textured soils.

46. Are appropriate backflow prevention devices in place and properly maintained if fertigation or chemigation is used?
Backflow prevention safety devices are used and properly maintained if fertigation or chemigation are used.
2.9 Irrigation Management Practices

47. Are appropriate backflow prevention devices in place and properly maintained if fertigation or chemigation is used?
Distance requirements between well and contamination, and agricultural chemical/fertilizer storage and preparation areas are at least 150 feet from the well.
2.11 Irrigation Management Practices

48. Irrigation management to Protect Groundwater
Backflow protection with Air gap and vacuum relief
-required for chemigation and fertigation
- good idea for all systems.
-Interlocks between nitrogen pump and irrigation pump.
-Backflow protection between injection point and supply tank.

49. Chemigation / Fertigation Systems - Safety Interlock

50. Are split applications of nitrogen fertilizer used when nitrogen is used in irrigated field?
Split applications of nitrogen fertilizer are used when nitrogen is used in an irrigated field. N application does not exceed MSU recommendation.
2.8 Irrigation Management Practices

51. Chemigation – Application of pesticide via irrigation water.
Fertigation – Application of fertilizer via irrigation water.