Evaluating Center Pivots in
Missouri
Joe Henggeler
University of Missouri
38th ANNUAL MISSOURI IRRIGATION CONFERENCE
Wednesday, Feb. 2, 2004
309 Hearnes Center, Columbia, MO
Team Up!



Irrigation Scheduling
Proper fertigation (corn)
Testing center pivots
Conducting a Test
Conducting a Test
Conducting a Test
Other Data Collected


Pivot age / total hours of operation
Pressure at beginning & end
Other Data Collected, cont.

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Type of sprinkler
Weather conditions during the test
Distribution Uniformity
DU =
Average catch of Low Quarter
Average catch
x 100
Irrigation Distribution Uniformity (DU)
2.5
Catch (inches)
2
Average Low Quarter catch = 0.8”
1.5
Catch
1
0.5
Average catch = 1.1”
0
0%
25%
50%
75%
% of the field this amount or less
100%
Irrigation Distribution Uniformity (DU)
DU = (0.8
 1.1) x
100 = 72%
2.5
Catch (inches)
2
Average Low Quarter catch = 0.8”
1.5
Catch
1
0.5
Average catch = 1.1”
0
0%
25%
50%
75%
% of the field this amount or less
100%
Evaluating Catch Amounts
10 ft
Evaluating Catch Amounts
0.8 “
10 ft
1.2 “
0.3 “
1.0 “
0.7 “
Evaluating Catch Amounts
0.8 “
1.2 “
0.3 “
1.0 “
10 ft
(1.2 + 0.3 + 1.0)“
3
= 0.8
(0.8 + 1.2 + 0.3)“
3
= 0.7
(0.3 + 1.0 + 0.7)“
3
= 0.7
0.7 “
Lots of data !
Problems with Systems
DU Value
Rating
> 75%
Excellent
65 – 74 %
Good
50 – 64 %
Fair
< 49 %
Poor
Results
Results, cont.
Results, cont.
Straight
Value
Averaging
Catch
Average
50 %
67 %
Maximum
82 %
86 %
Minimum
30 %
45 %
Locations of Pivots
Tested 2004
Tested 2003
Tested < 2003
The End
Joe Henggeler
Delta Center Research Center
573-379-5431
Henggelerj@missouri.edu