SL-213
Water Requirements for Drip-Irrigated Tomato
Production in Southwest Florida1
C.D. Stanley and G.A. Clark2
Water management in drip irrigated tomato amounts should then be scheduled to meet the crop
production requires information about the water ET requirements within the constraints of the
needs of the crop as well as the water holding irrigation system.
characteristics of the soil. Excessive irrigation can
leach crop nutrients from the root zone while soil Drip irrigation in Florida tomato production
moisture deficit can result in crop stress. This uses roughly 7200 feet of tube per production acre (6
publication will briefly present estimates of tomato ft bed spacing). Drip tubing water discharge is
plant water requirements under drip irrigated generally rated as flow per unit length, such as 0.5
conditions for crops produced in the southwest gallons per minute (gpm) per 100 feet. Therefore,
Florida region. tubing water discharge per production acre would be
about 36 gpm. This information is necessary for
Reference evapotranspiration (Eto) refers to the properly scheduling irrigations. Table 2 converts
expected water use from a uniform green cover crop tubing flow in gpm per 100 feet to gallons per hour
surface such as a grass. Actual crop use is generally (gph) per 100 feet, gallons per minute per acre, and
less and is determined by using a crop coefficient run time in minutes needed to apply 1000 gallons per
relating crop ET (ETc) to ETo. Reported values of acre at 100% efficiency. Actual irrigation time will
ETo are generally expressed as inches of water use be longer due to system inefficiencies, soil
over the surface. This choice of units is appropriate conditions, and crop cultural characteristics.
for use with sprinkler irrigation systems. However, However, Table 2 may be used with Table 1 to
volumetric units are more appropriate for drip establish initial management guidelines. For
systems. Actual crop ET depends on reference ET as example, the initial plant water requirements for
well as crop development. Typical daily ETc values plants set in August are estimated at 1000 gallons per
for the southwest Florida area during the fall and acre per day. This requires 28 minutes of run time for
spring tomato production periods for several a tube that discharges 0.5 gpm/100 ft and that applies
transplanting periods are provided in Table 1. Values water @ 100% efficiency. However, some
are expressed as gallons per acre per day. Irrigation commercial systems may require 35 to 45 minutes of
1. This is document SL-213, a publication of the Soil and Water Science Department, Florida Cooperative Extension Service, IFAS, University of Florida.
Published February 2004. Reviewed August 2009. Please visit the EDIS Web site at http://edis.ifas.ufl.edu
2. C.D. Stanley, professor, Soil and Water Science Department, Gulf Coast Research and Education Center, Florida Cooperative Extension Service,
University of Florida, Gainesville, FL; G.A. Clark, professor, Biology and Agricultural Engineering, Kansas State University, Manhattan, Kansas.
The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and
other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex,
sexual orientation, marital status, national origin, political opinions or affiliations. U.S. Department of Agriculture, Cooperative Extension Service,
University of Florida, IFAS, Florida A. & M. University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Millie
Ferrer, Interim Dean
Water Requirements for Drip-Irrigated Tomato Production in Southwest Florida 2
run time to move the applied water from the water
source, through the pipe network, and from the
dripper into the root zone of the crop.
Soil properties should also be known and
monitored for an effective irrigation management
program. The volume of readily available water to
the crop depends on the soil water holding properties
and the crop root zone. Water should be applied
when no more than half of the available water has
been depleted. For a well-developed, drip-irrigated
tomato crop, the root zone may extend 8 to 10 inches
from the drip tube. The amount of water that would
be available to the crop between field capacity and
50% depletion may range from 1000 gallons per acre
for very coarse sand, to 2000 gallons per acre on
medium to fine textured sands, to in excess of 3000
gallons per acre on some of the heavier, finer textured
soils. Therefore, some sandy soils with low water
holding capacities will require frequent irrigations
(such as daily) with relatively short durations during
low crop ET periods or even multiple cycles per day
during high crop ET periods. However, soils with
greater water holding capacities can be managed with
less frequent irrigations and longer irrigation
durations. The irrigation run time should be
sufficient to re-wet the active root zone, apply needed
chemicals (fertilizers), and meet the constraints of
the irrigation system and scheduling program.
Proper water management in drip irrigated
production systems requires knowledge of crop water
requirements, soil water holding and water
distribution properties, and close monitoring of the
irrigation system, the crop, and atmospheric
conditions. The information in this report is provided
for use as initial guidelines for developing an
effective and conservative water management
program. Because actual field conditions and
requirements vary, this information is intended for
general management purposes only.
Water Requirements for Drip-Irrigated Tomato Production in Southwest Florida 3
Table 1. Estimated crop ET values for drip irrigated tomato plants in the southwest Florida area expressed in gallons per acre
per day at five periods of time based on Days After Transplanting (D.A.T.) for transplants set at different periods. (This table
assumes 6 foot bed centers or 7260 linear bed feet per acre.)
D.A.T. Month of Transplanting
Aug Sept Oct Jan Feb Mar
gallons per acre per day
0-20 1000 1000 1000 600 800 900
20-40 2400 2200 2000 1800 2000 2200
40-60 3600 3200 2200 3200 3800 4000
60-80 3200 2700 2000 4000 4600 4600
80-100 2100 1800 1800 3600 4000 4000
Table 2. Comparison of tubing flow rates to irrigation discharge per acre and run time needed to apply 1000 gallons per acre
at 100% efficiency. (This table assumes 6 foot bed centers of 7260 linear feet per acre.)
Tubing Flow Rate Irrigation Time to Apply
(gpm per 100 feet) (gph per 100 feet) (gpm per acre) (minutes @ 100% eff.)
0.2 12 14 71
0.3 18 22 45
0.4 24 29 34
0.5 30 36 28
0.6 36 43 23
