April 26, 2016
Jason Coleman, P.E.
General Manager
High Plains Underground Water Conservation District
2930 Avenue Q
Lubbock, TX 79411-2499
Subject: Progress Report- HPWD Research and Demonstration Project, “Conserving Agricultural Water
with Traveling Drip Irrigation, Low Energy Precision Application, and Low Elevation Spray Application”
Progress made to date: In the growing season of 2015, a field study was conducted to compare corn
yields (biomass and grain), evapotranspiration and crop water productivity between irrigation methods
of precision mobile drip irrigation (PMDI) (DragonLine™), low energy precision application (LEPA) and
low elevation spray application (LESA). Plots for the three application methods were arranged in the first
and fifth spans to investigate any influence of flow rate on crop production and replicated three times in
each span. Dripline length for the PMDI was sized from 26 to 34 feet in the first span, and from 71 to 78
feet in the 5th span. Flow meters were installed in three PMDI drops (two in the 1st span and 1 in the 5th
span) to help detect emitter clogging. Weekly soil water readings were made with the neutron probe for
each of the 18 plots and averaged across treatment method in each span. Irrigation amounts for each
type of treatment method was applied to replenish soil water depletion to field capacity. Plant height
and width measurements were made periodically throughout the growing season. Grain and biomass
yields were harvested by hand in each treatment plot.
Setbacks and successes: A hail storm that occurred on June 14, 2015 devastated the corn planted in mid
May 2015. Corn was replanted on June 23 to a short season drought tolerant hybrid (Pioneer P0157 with
relatively maturity of 101 days). Cumulative rainfall at Bushland from June through September 2015 was
15.4 inches. Despite the severe weather event and plentiful rainfall, soil water and plant measurements
were made regularly throughout the season. Irrigation amounts and yields were similar for all three
application methods. There was no evidence of emitter clogging; water was filtered at each drop prior to
the conversion from drop hose to dripline. Crop water use efficiency or the ratio of grain yield in LESA
and LEPA plots were similar to corn irrigated by the PMDI method (Table 1).
Table 1. Irrigation applied and crop response for corn (P0157) for each application method grown at Bushland,
Texas during the 2015 cropping season.
Application
Method
Irrigation
Applied
(inches)
Adjusted
Yield
(Bu/acre)
LESA
11.4
182a
PMDI
12.4
177a
LEPA
12.3
171a
*Adjusted to 15.5% moisture
ƚ
HI- harvest index
Seasonal
Crop Water
Use (inches)
20.4a
21.6a
21.8a
Water Use
Efficiency
(Adjusted
Bushels*/acrein)
8.9a
8.3ab
7.8b
Kernel
Weight
(mg)
Kernels/ear
Biomass
(g)
HIƚ
265a
261a
258a
453a
451a
448a
3042a
3002a
3075a
0.54a
0.55a
0.55a
Conservation impacts to the district: PMDI demonstrated advantages over LESA and LEPA in terms of
irrigation management; observations were that PMDI reduced soil surface wetting during early
irrigations, after emergence and prior to the V-4 stage as compared to LEPA and LESA. In addition, PMDI
located near the center pivot drive trains helped to maintain relatively dry wheel tracks as compared
with the other application methods. As compared with LEPA, PMDI provides a more manageable means
to apply water and prevent run-off (Fig. 1). The installation of the PMDI system could be improved by
increasing the rigidity of its infrastructure to help maintain the dripline between crop rows (this revision
was recently accomplished) and prevent the dripline from climbing onto the crop (Fig. 2). Furrow-diking
and planting in circles using GPS guidance tractors are also key farming practices to facilitating the
application efficiency of PMDI. In a drier growing season, it is anticipated that crop water use efficiency
will be greater with PMDI than LEPA.
Figure 1. Dripline located near wheel track.
Figure 2. Dripline climbing onto corn crop.
Budget expense report and remaining grant funds available: all funds for supplies were spent on
installation of equipment for adapting the drop hoses to the DragonLine™ system, LEPA socks and three
flow meters (Table 2). The remaining funds of $7,000 are for salaries and will be spent this summer to
hire a student to perform soil water and plant measurements, as well as help maintain the field and
record observations.
Table 2. Budget
Category
Supplies
Salary/Benefits
ARS In-Kind Funds
Spent to Date
$1941.32
$9,000
Funds Spent to Date
Remaining Funds
$2000.00
$0.00
$0.00
$7,000