L miller texas live oak growth with tensiometer-controlled cyclic irrigation
1. Live Oak Growth with Tensiometer-controlled Cyclic Irrigation
Tensiometer-
Laura Miller
Texas AgriLife Extension, Tarrant County, Fort Worth, TX 76102
Tom Yeager and Claudia Larsen
Dept. Environmental Horticulture, Univ. of Florida, IFAS, Gainesville, FL 32611
Abstract Results
Efficient use of water resources in plant Tree heights and calipers were not different at
production is important for sustainability. each date (Fig. 1) when cyclic irrigation was
Irrigation water is often thought of as a low automatically applied three times daily, or
cost input, but over-application wastes this cycles of irrigation were applied when
valuable resource. Cyclic irrigation has been
container moisture tension exceeded 5 kPa as
shown to result in 50% less irrigation water
determined with tensiometers. The growth
applied without sacrificing live oak growth
(Beeson and Haydu, 1995). The use of soil reduction was due to pruning.
moisture sensors to prevent irrigation when
substrate water content is above a critical Live Oak Heights
level further reduced irrigation volume
5
applied, while still providing sufficient water
for plant growth. Tensiometers integrated with 4
an irrigation controller limited cyclic irrigation
Height (m)
3
applications to when moisture tensions were >
2
5kPa (5 centibars) and resulted in a 62 %
reduction in the volume of water applied 1
compared to a fixed daily three cycle irrigation 0
schedule. Because tree growth was not 7/24/2006 10/13/2006 12/18/2006 3/21/2007 8/15/2007 11/2/2007 2/25/2008
negatively affected, these results indicate that Tensiometer Cyclic Daily
the Best Management Practice of scheduling
irrigation based on substrate moisture is an
effective way for container tree producers to Live Oak Calipers
conserve water. 50
40
Methods
Caliper (mm)
30
Live oak trees (Quercus virginiana ‘Cathedral’ #3 container)
were planted May 2006 with a commercially prepared 6 pine 20
bark: 4 Florida peat: 1 sand substrate (by volume) in
10
containers called “The Smart Pot.” [24 inches diameter and
≈14 inches high (High Caliper, Inc., Oklahoma City, OK]. 0
8/3/06 10/13/06 12/18/06 3/21/07 8/15/07 11/2/07 2/25/08
The substrate was amended with dolomitic limestone and Tensiometer Cyclic Daily
Florikan® Blend 15-4-9 controlled-release fertilizer
(Florikan, Sarasota, FL) was applied during potting by Fig. 1. Live oak heights and calipers ± standard deviation.
distributing 1 lb of fertilizer around the roots of the
transplant as the container was filled and all trees were The integration of tensiometers into irrigation
subsequently fertilized the same. Trees were placed 5 ft
control resulted in 62% less water applied
apart in a guy-wire supported row at Sun City Tree Farm,
Ruskin, FL. compared to a fixed schedule of cyclic
irrigation events (Fig. 2). Even though less
Irrigation was applied via one Chapin spray stake type P irrigation water was applied, tensiometers
per container [(0.6 qt/min≈12 psi) Chapin Watermatics,
required monitoring and maintenance to
Inc.,Watertown, NY]. A water meter was installed in the
main irrigation supply line for each of four irrigation zones. ensure proper operation.
Switching tensiometers (Irrometer Model “LT”, Irrometer Water Applied to Live Oaks
Company, Inc., Riverside, CA) were used to activate
irrigation cycles when the substrate moisture tension was 60,000
greater (drier) than 5 kPa (5 centibars) during any of three 50,000
scheduled activation times each day (mid-morning, mid-
Acknowledgements 40,000
Irrigation (gal)
afternoon, and late afternoon) or three irrigation cycles
were automatically activated daily by preset controller for a The authors acknowledge the cooperation of 30,000
Sun City Tree Farm, Ruskin, FL and support of
total of ≈ 2 gal/tree at beginning of study and 3.4 gal/tree at
the Florida Agricultural Experiment Station, 20,000
end. FNGLA Endowed Research Fund, and the
Tampa Bay Wholesale Growers LAA. 10,000
Tree heights, calipers, and meter readings were determined
0
July 24 (Aug. 3 for caliper), Oct. 13, and Dec. 18, 2006; Mar Tensiometer Cyclic Daily
21, Aug. 15, and Nov. 2, 2007; and Feb. 25, 2008.
Fig. 2. Irrigation water applied from July 2006 to Feb. 2008.
![Live Oak Growth with Tensiometer-controlled Cyclic Irrigation
Tensiometer-
Laura Miller
Texas AgriLife Extension, Tarrant County, Fort Worth, TX 76102
Tom Yeager and Claudia Larsen
Dept. Environmental Horticulture, Univ. of Florida, IFAS, Gainesville, FL 32611
Abstract Results
Efficient use of water resources in plant Tree heights and calipers were not different at
production is important for sustainability. each date (Fig. 1) when cyclic irrigation was
Irrigation water is often thought of as a low automatically applied three times daily, or
cost input, but over-application wastes this cycles of irrigation were applied when
valuable resource. Cyclic irrigation has been
container moisture tension exceeded 5 kPa as
shown to result in 50% less irrigation water
determined with tensiometers. The growth
applied without sacrificing live oak growth
(Beeson and Haydu, 1995). The use of soil reduction was due to pruning.
moisture sensors to prevent irrigation when
substrate water content is above a critical Live Oak Heights
level further reduced irrigation volume
5
applied, while still providing sufficient water
for plant growth. Tensiometers integrated with 4
an irrigation controller limited cyclic irrigation
Height (m)
3
applications to when moisture tensions were >
2
5kPa (5 centibars) and resulted in a 62 %
reduction in the volume of water applied 1
compared to a fixed daily three cycle irrigation 0
schedule. Because tree growth was not 7/24/2006 10/13/2006 12/18/2006 3/21/2007 8/15/2007 11/2/2007 2/25/2008
negatively affected, these results indicate that Tensiometer Cyclic Daily
the Best Management Practice of scheduling
irrigation based on substrate moisture is an
effective way for container tree producers to Live Oak Calipers
conserve water. 50
40
Methods
Caliper (mm)
30
Live oak trees (Quercus virginiana ‘Cathedral’ #3 container)
were planted May 2006 with a commercially prepared 6 pine 20
bark: 4 Florida peat: 1 sand substrate (by volume) in
10
containers called “The Smart Pot.” [24 inches diameter and
≈14 inches high (High Caliper, Inc., Oklahoma City, OK]. 0
8/3/06 10/13/06 12/18/06 3/21/07 8/15/07 11/2/07 2/25/08
The substrate was amended with dolomitic limestone and Tensiometer Cyclic Daily
Florikan® Blend 15-4-9 controlled-release fertilizer
(Florikan, Sarasota, FL) was applied during potting by Fig. 1. Live oak heights and calipers ± standard deviation.
distributing 1 lb of fertilizer around the roots of the
transplant as the container was filled and all trees were The integration of tensiometers into irrigation
subsequently fertilized the same. Trees were placed 5 ft
control resulted in 62% less water applied
apart in a guy-wire supported row at Sun City Tree Farm,
Ruskin, FL. compared to a fixed schedule of cyclic
irrigation events (Fig. 2). Even though less
Irrigation was applied via one Chapin spray stake type P irrigation water was applied, tensiometers
per container [(0.6 qt/min≈12 psi) Chapin Watermatics,
required monitoring and maintenance to
Inc.,Watertown, NY]. A water meter was installed in the
main irrigation supply line for each of four irrigation zones. ensure proper operation.
Switching tensiometers (Irrometer Model “LT”, Irrometer Water Applied to Live Oaks
Company, Inc., Riverside, CA) were used to activate
irrigation cycles when the substrate moisture tension was 60,000
greater (drier) than 5 kPa (5 centibars) during any of three 50,000
scheduled activation times each day (mid-morning, mid-
Acknowledgements 40,000
Irrigation (gal)
afternoon, and late afternoon) or three irrigation cycles
were automatically activated daily by preset controller for a The authors acknowledge the cooperation of 30,000
Sun City Tree Farm, Ruskin, FL and support of
total of ≈ 2 gal/tree at beginning of study and 3.4 gal/tree at
the Florida Agricultural Experiment Station, 20,000
end. FNGLA Endowed Research Fund, and the
Tampa Bay Wholesale Growers LAA. 10,000
Tree heights, calipers, and meter readings were determined
0
July 24 (Aug. 3 for caliper), Oct. 13, and Dec. 18, 2006; Mar Tensiometer Cyclic Daily
21, Aug. 15, and Nov. 2, 2007; and Feb. 25, 2008.
Fig. 2. Irrigation water applied from July 2006 to Feb. 2008.](https://image.slidesharecdn.com/lmillertexasliveoakgrowthwithtensiometer-controlledcyclicirrigation-100826163515-phpapp02/85/l-miller-texas-live-oak-growth-with-tensiometercontrolled-cyclic-irrigation-1-320.jpg)
