Drip Irrigation Research
in Arkansas
Earl Vories
University of Arkansas
Northeast Research & Extension Center
Keiser, Arkansas
Center Pivot and Furrow Irrigation
Common in the Mid-South
Blytheville
Leachville
Satellite
Image of
NE Ark.
Aug., 99
Manila
Osceola
Drip Irrigation Getting Interest
• Earlier use in arid areas (AZ, west TX,
Israel).
• Efficient use of limited water.
• Allows injection of fertilizers/other
products in root zone.
• More recently being investigated in
humid areas (southeast, mid-south).
Current research efforts in
Arkansas using precise water
control possible with drip
irrigation to investigate
irrigation scheduling, rather
than investigating the optimal
drip irrigated production
system.
Change in Water Use With Crop Age
Typical* Water Use (in.)
0.4
Last Ef f ect ive Flower
Cotton
0.3
(80 DAP - mid-August )
Plant ing
First Square
(32-38 DAP)
First Flower
(57-63 DAP)
0.2
First Open Boll
Emergence
(>100 DAP)
(4-10 DAP)
0.1
0
27-Apr
* based on Keiser
30-yr mean Tmax
25-May
22-Jun
20-Jul
Date (for May 1 planting)
17-Aug
Computerized Irrigation Scheduler
Distributed by University of Arkansas
Cooperative Extension Service
(www.uaex.edu)
Computerized Irrigation Scheduler
Computerized Irrigation Scheduler
est. 30-yr ETr (63-92)
Reference Evapotranspiration (Etr)
0.4
Keiser
0.3
0.2
0.1
0.0
10-Apr
29-May
17-Jul
04-Sep
23-Oct
Crop Coefficient (ET/ETr)
Crop Coefficient Function - Cotton
1.2
Last Effective Flower
(80 DAP - mid-August)
Cotton
1
First Flower
(57-63 DAP)
0.8
First Square
(32-38 DAP)
Planting
0.6
First Open Boll
(> 100 DAP)
Emergence
(4-10 DAP)
0.4
0.2
0
-10
11
32
53
74
Crop Age (days after emergence)
95
Crop Coefficient (ET/ETr)
Crop Coefficient Function - Corn
1.1
Corn
0.9
0.7
0.5
0.3
0.1
0
20
40
60
80
100
Days After Emergence
120 140
As you would expect, many
differences between the drip
irrigation systems on a
production-field scale and a
small-plot research scale.
Field Scale
System Controls
Small Plot
Injector Pumps
for Water Conditioners (generally required for groundwater)
Fertilizers, Soil Conditioners, etc.
Filter Bank for Groundwater
Field Scale
RPZ Valve and Screen for Municipal Water
Small Plot
Solenoids for Controlling Water
Small Plot
Field Scale
Lateral Lines Feeding Individual Drip Lines
Small Plot
Field Scale
Much of 2001 growing season
spent installing and testing
irrigation/control/monitoring
systems, probably reducing
potential responses.
Estimated Soil Water Deficits - Corn
7
6
No Irr.
SWD (in.)
5
Irrigation System
Began Operation
4
75% ET
3
2
1
0
4/29
125% ET
5/13
5/27
6/10
6/24
7/8
7/22
8/5
Corn Yields (bu/acre)
200
180
160
140
120
100
80
60
40
20
0
Yields not significantly
affected by water
treatments.
T 2160 BT
P 34B24 BT
DK C69-70 BT
No Irr.
75% ET 125% ET
Later season allowed more
observations in cotton study,
more treatment differences
observed.
Estimated Soil Water Deficits - Cotton
7
SWD (in.)
6
5
4
3
No Irr.
60% ET
Irrigation System
Began Operation
2
100% ET
1
0
5/10
5/31
6/21
7/12
8/2
8/23
9/13
Watermark sensor
Output from Watermark Sensors - Cotton
3.5
Final Irrigation
Tension (bars)
3.0
2.5
No Irr.
2.0
1.5
60% ET
1.0
0.5
100% ET
0.0
7/22 7/30 8/7 8/15 8/23 8/31 9/8 9/16 9/24
Crop Response to Water
100% ET
No Irrigation
Physiological Cutout (NAWF=5, DAP)
86
84
82
80
78
76
74
72
70
68
66
SG 747
PSC 355
NuCotn 33B
No Irr.
60% ET
100% ET
Mean Maturity (DAP)
145
140
135
SG 747
PSC 355
NuCotn 33B
130
125
120
No Irr.
60% ET
100% ET
Seedcotton Yields (lb/acre)
Yields not
significantly affected
by water treatments.
3500
3000
2500
2000
SG 747
PSC 355
NuCotn 33B
1500
1000
500
0
No Irr.
60% ET
100% ET
Conclusions from 2001
• System/equipment functioning well.
• Installation of drip tubing (subsoiling every
row) in spring, as well as delays in planting
and irrigating due to installation probably
affected responses in initial season.
• Drip irrigation system appears to provide
desired water control for studying irrigation
scheduling.
Acknowledgment
Research supported by Arkansas
corn and cotton producers through
checkoff programs.