A Comparative Agronomic Analysis of Subsurface Drip
and Overhead Irrigation of Georgia Cotton
Jared Whitaker, Craig W. Bednarz, Glen Ritchie, and Cory Mills
The University of Georgia
Subsurface Drip vs. Overhead Irrigation Irrigation of Treatments The overhead treatment had 100
8 inches
Overhead irrigation systems are widely used in The overhead irrigated plots were watered by a increasingly higher soil water readings 80
irrigated cotton farmland. However, the linear sprinkler system. Both SSD treatments were in the later part of the year than either 60
success of subsurface drip systems in other watered by a drip irrigation system that consisted of drip treatment, even though the water
40
crop systems has led researchers and 12” deep drip line in the center of every other row. output was the same as SSD matched
producers to consider it as an alternative to The drip irrigation system was controlled by inputs to the irrigation and more than for the 20
overhead irrigation. However, the profitability from the Adcon telemetry units. When watermark SSD based on ET plots. 0
of subsurface drip compared to overhead reading triggered the irrigation, the automatic This trend was especially evident at 24”
Reading (-cbar)
16 inches
80
irrigation has not been widely assessed in the irrigation system watered the plots. The treatments readings, suggesting that water from
Southeast. were watered independently of each other by the the overhead irrigation did not 60
Drip irrigation can reduce water loss through soil evaporation, and station pictured to the right. penetrate the soil as far as that from 40
advantages of drip include more efficient water use, quicker either of the drip treatments. 20
application to crops approaching water deficit, and the ability to farm 7
square fields efficiently without the loss of land at the corners. The
Monitoring Soil Water Status 6 Overhead 0
Applied (inches)
SSD based on ET
University of Georgia is comparing overhead irrigation and drip irrigation 5 SSD Matched 80
24 inches
Total Water
for efficiency and cost. Watermark sensors were installed in two replicates of 4 Overhead
60 SSD based on ET
each treatment. The sensors were placed between 3 SSD matched
the center two rows of the plot. One set was placed Adcon 40
transmitter 2
in the row center at the depths of 6”, 24”, and 36”. 20
1
Another set was placed 4” away from the cotton at
0 0
depths of 8”, 16”, and 24”. Irrigation was triggered in 07/05 07/12 07/19 07/26 08/02 08/09 06/14 06/28 07/12 07/26 08/09
a treatment when any of the watermarks read above Adcon
receiver Date Date
40 cb. Adcon telemetry equipment was also installed
in one replicate of the four treatments to continously There are significant water use differences within the watering systems.
monitor soil water status. Watermark
The SSD based on ET used 27% less cumulative applied water than the
sensors
overhead irrigated treatment. The decreased water use of the SSD
Plot Design
based on ET treatment compared to the overhead irrigation for the
2004 experiment was approximately 46,000 gallons per acre.
The experiment was conducted at the Stripling Irrigation Research Park
in Camilla, GA using Delta Pine 488BR at a density of three plants per
Ginning The lint yield from the SSD 1400
foot. was comparable to that of A
The cotton picked from the plots was ginned and weighed at the 1200 A
Lint Yield (lb/acre)
AB
Plot layout consisted of a randomized block design with 4 irrigation the overhead irrigation
SSD II based on ET
University of Georgia Micro-gin, a state-of-the-art ginning facility in Tifton, 1000
treatments and 4 replicates. The plots were 60 ft long and 30 ft wide Georgia. Quality samples were taken and sent to Cotton Incorporated treatment. Both the
800 B
on Overhead
with 30 ft borders, and the middle two rows were used for data overhead irrigation and the
SSD I based
for HVI analysis.
Overhead
collection. subsurface drip were 600
Dryland
TREATMENTS significantly higher than the 400
1. Overhead Irrigation Data Analysis non-irrigated. All of the
200
2. Subsurface Drip Irrigation based on crop evapotranspiration (SSD Data Analysis of cotton growth and yield among all irrigation systems had
based on ET) treatments was performed in SAS 8.0, using ANOVA at a statistically the same yields. 0
3. Subsurface Drip Irrigation matching overhead irrigation rate (SSD confidence level of 0.05 and Tukey’s pairwise test. Irrigation Treatment
matched)
The 2004 results suggested that subsurface drip is more efficient than
4. Non-Irrigated
Results 10
overhead irrigation and can give comparable yields with less water
output.
Overhead
The nodes above A
Acknowledgements
8 AB SSD ET
first square/white
BC SSD Matched
A A
C A
NAFS/WF
6
AB Dryland
flower graph A A A
A
B B AB A
B B Funding for this research was provided by Cotton Incorporated.
suggests that the 4
C
C
A
A A A
B B
dryland plots
Contact
2
reached cutout C B
Jared Whitaker Craig Bednarz
0
more rapidly than July 8 July 16 July 23 Aug 2 Aug 6 Aug 13 Aug 20 email: jrwhit@uga.edu email: cbednarz@uga.edu
the irrigated treatments, but also that the subsurface drip plots matured 229-391-2695 229-391-2513
1. Overhead irrigation 3. SSD based on overhead rate
more quickly than the overhead irrigation.
2. SSD based on ET 4. Non-irrigated