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Group Title: Research report - North Florida Research and Education Center ; 90-17
Title: Irrigation use by mulched staked tomatoes in north florida
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Permanent Link: http://ufdc.ufl.edu/UF00066086/00001
 Material Information
Title: Irrigation use by mulched staked tomatoes in north florida
Series Title: Research report (North Florida Research and Education Center (Quincy, Fla.))
Physical Description: 14 leaves : ill. ; 28 cm.
Language: English
Creator: Rhoads, Fred ( Frederick Milton )
North Florida Research and Education Center (Quincy, Fla.)
Publisher: North Florida Research and Education Center
Place of Publication: Quincy Fla
Publication Date: 1990
 Subjects
Subject: Crops and water   ( lcsh )
Tomatoes -- Florida   ( lcsh )
Genre: bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Includes bibliographical reference (p. 13).
Statement of Responsibility: by F.M. Rhoads.
General Note: Caption title.
 Record Information
Bibliographic ID: UF00066086
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 71154173

Table of Contents
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        Page 1
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        Page 6
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        Page 13
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Full Text

NFREC, Quincy Research Report 90-17


Irrigation Use by Mulched

Staked Tomatoes in North Florida

By ,

F. M. Rhoactdss 2
~~ ^, o. ,, ^ '"0


Florida Agricultural Experiment Stations
Institute of Food and Agricultural Sciences
University of Florida, Gainesville


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Irrigation Use by Mulched

Staked Tomatoes in North Florida

F. M. Rhoads

Water management districts in Florida are encouraging crop

producers to use water for irrigation more efficiently because of

increased demand on the water supply by a rapidly increasing

population. More efficient water use (i.e. greater crop production

per unit of water used) makes water available to more users and

reduces nutrient leaching and pesticide movement in soil profiles.

Irrigation use permits are required in order for tomato growers and

other irrigation users to withdraw water from wells and streams.

Permits for irrigation use are based on both a maximum daily use

rate and seasonal total amount. Therefore, the purpose of water

use permits is two fold, first to conserve water and second to

protect the environment.

This report was written to provide tomato growers with a

source of data on which to base requests for irrigation use

permits. Tomato growers need to be assured that adequate water use

is permitted to produce a profitable yield while water management

officials are concerned about conservation in order for everyone to

have water. Irrigation use and tomato fruit yields are reported

for three experiments covering a wide range of environmental

conditions. Seasonal irrigation use was calculated for a 120-day

growing season, therefore, actual irrigation use will vary with

length of growing season. The purpose of this report is not to

establish a daily water use rate or seasonal amount of irrigation










to be permitted for tomato production, but to provide some unbiased

data that should be helpful to water management officials and

tomato growers in negotiating irrigation use permits.

METHODS AND MATERIALS

Experiment #1: Field plots were transplanted with tomato

plants of the Walter cultivar on 19 March during a relatively dry

growing season. Plant rows (six feet apart) were located on beds

three feet wide covered with black plastic mulch. Spacing between

plants was two feet with wood stakes driven into the ground between

plants with twine attached to prevent plants from falling over. A

fumigant was applied just before the plastic mulch to control

pests. Soil type was Tifton loamy fine sand (fine, loamy,

siliceous, thermic, Plinthic Kandiudult).

There were three irrigation treatments: sprinkler (SI),

automatic drip (ADI), and manual drip (MDI). All treatments were

scheduled for irrigation with tensiometers (one per plot) placed

six inches from plants with the sensor at the six-inch depth.

Therefore, plant demand for water determined the amount of

irrigation used in each treatment. Irrigation was turned on for

each treatment when the reading reached 20 centibars (cb). One bar

is equal to 14.5 lbs/square-inch of negative pressure or suction;

20 cb = 0.2 bar or 2.9 Ibs/square-inch of suction. Treatments SI

and MDI were irrigated with one-inch and 0.2 inches of irrigation

at each application, respectively. Treatment ADI had a switching

tensiometer connected to a solenoid that turned the irrigation on

above 20 cb and off below 20 cb. A municipal type water meter was










used to measure the amount of irrigation applied. Meter accuracy

was checked with standard volumetric containers. Via-flow (a white

porous plastic) drip tubing was used in treatments ADI and MDI.

Sprinkler irrigated (SI) plots had dykes constructed between rows

to prevent runoff from the four small radius sprinklers in each

plot.

One-thousand lbs/acre of a 3-14-4 mixture was incorporated

into plant beds of all treatments to supply 30 lbs/acre N, 60

lbs/acre P, and 30 lbs/acre K (N = nitrogen, P = phosphorus, and K

= potassium). A 19-0-24 mixture (1100 lbs/acre) was applied to

supply 200 lbs/acre N and 200 lbs/acre K. The 19-0-24 was applied

in bands six inches from the plant row on each side of the bed to

treatment SI. One band of 19-0-24 was applied to treatment ADI

between the drip tube and plants to evaluate the influence of high

fertilizer salt concentration on tomato yield. In treatment MDI,

the 19-0-24 was dissolved in water, filtered and injected into the

drip tubing at weekly intervals to supply 20% of the total during

the first seven weeks of growth and the remainder between 8 and 13

weeks.

Tomatoes were hand-harvested at two or three day intervals, a

total of ten times. Yield is reported in tons/acre of pink and

mature green fruit of marketable sizes.

Experiment #2: Tomato plants of the Sunny cultivar were

transplanted in field plots on 8 April in a year with higher

rainfall than for experiment #1. Soil type was Orangeburg loamy

fine sand (fine, loamy, siliceous, thermic, Typic Kandiudults).










Fertilizer and pest control chemicals were applied uniformly to all

plots. Row width was six feet and distance between plants was 20

inches. Plots were mulched and staked as in experiment #1.

Two frequencies and four rates of drip irrigation were

compared in a factorial arrangement. Daily irrigation was compared

with irrigation applied Monday, Wednesday, and Friday (MWF) for a

given amount of water per week. The four irrigation rates were 25,

50, 75, and 100% of 0.2 inches d'1 from 8 April to 15 May and 0.3

inches d'1 from 16 May to 15 July. An automatic timing system

turned irrigation on and off for individual treatments. Emitter

(12 inch spacing) flow rates from twin wall drip tubing

manufacturer's specifications were used to calculate the time

required to apply each irrigation rate.

Rainfall and evaporation data for Exp-1 and Exp-2 were

obtained from weather records maintained by the National Oceanic

and Atmospheric Administration (NOAA).

Mature green and pink fruit were harvested on each of the

following dates: 23 and 29 June and 7 and 15 July. Yields are

reported as marketable fruit in tons per acre.

Experiment #3: Plywood boxes 36 x 20 x 18 inches (L x D x W)

containing 6 inches of topsoil over 12 inches of subsoil were used

to grow plants of the Sunny tomato cultivar under a transparent

rain shelter. The soil, Greenville loamy fine sand clayeyy,

kaolinitic, thermic, Rhodic Kandiudults), was packed approximately

to field bulk density. Fertilizer materials and chemicals for pest

control were applied uniformly to all treatments.









Water was applied through drip tubing underneath black plastic

mulch. One treatment received 0.24 inches of irrigation when

tensiometer readings were >20 cb (tensiometers were placed 6 inches

from plants with sensors 6 inches deep). Use of tensiometers allow

irrigation to be applied in accord with plant demand. Other

treatments consisted of two rates of irrigation with each applied

at two irrigation frequencies. Irrigation rates were 0.03 (rate-l)

and 0.06 (rate-2) inches per day from 0 to 7 weeks and 0.06 (rate-

1) and 0.12 (rate-2) inches per day from 8 to 12 weeks after

planting. Frequencies were daily and Monday, Wednesday, and Friday

(MWF) for each rate.

Fruit was harvested on 16 and 27 June and ripe fruit, green

fruit and total fruit weights were determined.

Statistical evaluation of data: The experimental design was

a randomized complete block with four replications for all

experiments except Exp. #1 which had three replications.

Regression analysis procedures were used to evaluate yield response

to amount of irrigation. Analysis of variance procedures and

orthogonal contrasts were employed to make appropriate comparisons

between individual treatments (Steel and Torrie, 1960).

RESULTS AND DISCUSSION

Rainfall during the growing season for Exp-1 was below normal

(Fig. 1). Total rainfall for April, May and June was 4.92 inches

or 0.06 inches per day seasonal average for Exp-1. Growing season

rainfall for Exp-2 was above normal in March and June, and below

normal in April, May and July. Only 0.35 inches of rainfall











occurred in April and average daily rainfall for May was 0.1 inches

per day. Total rainfall for June was 8.34 inches. Normal rainfall

amounts for March, April, May, June, and July are 5.23, 4.89, 4.28,

5.22, and 6.90, respectively (Davis and Mickelson, 1969). There-

fore, the normal average daily rainfall during the growing season

of spring planted tomatoes in Gadsden County is 0.17 inches per

day. However, rainfall in individual years can vary widely from

the norm as shown in Figure 1. Tomato plants in Exp-3 were grown

under a transparent rain shelter in order to provide a better

estimate of actual water use by tomato plants.

Rainfall (Inches/day) Rainfall (inches/day)
1 2.5
Expflment ExpWlment
0.8 2x. Exp. 21
E Exp. #2 V Exp. #2
0.0 1.6

0.4 10

0.2 i | I I 0 I |

Ap-4 17 19 23 24My-8 9 11 12 14 16 1 17 19 21 22 27 29 31 Jn-26 7 13 14 15 1 177 0 1 20 21 22232426 2 27Jy-13 4 5 7 8 10 11
Day of Month Day of Month

Figure 1. Rainfall for exp. #1 and exp. #2 from 1 April to 15

July.

Tensiometer scheduling provides irrigation at approximately

the rate of plant use. Manual and automatic drip irrigation

treatments used about the same amount of irrigation (Fig. 2). This

was expected and verifies the effectiveness of the switching

tensiometer. Total irrigation for the drip system was about 10

inches compared with almost 39 inches for the sprinkler system.

The sprinkler system, with no runnoff allowed, was only about 25%










as effective as drip irrigation in supplying water to tomato

plants. Plastic mulch sheds most of the irrigation from sprinklers

and movement of water from the middles to plants is not very

efficient. Rainfall would be less than 25% efficient if runoff

occurred. Estimated total water use (98 days) for drip irrigated

tomatoes was 13 inches based on rainfall being 25% as effective as

drip irrigation. Average daily irrigation use with sprinklers was

0.23 inches/day between 19 March and 2 May and 0.53 inches/day

between 2 May and 29 June. Drip irrigation used 0.03 inches/day

between 19 March and 2 May and 0.17 inches/day between 2 May and 24

June. Estimated drip irrigation use in Exp-1 for 120 days is 14.2

inches. Maximum daily irrigation was 1.0 inch for sprinklers and

0.23 inches for drip.

Accumulative Irrigation Use (Inches)
40
Irrigation System
-1 Sprinkler
80 -ES Manual Drip
E Automatic Drip

20


10-



Mr-19 Ap-lO My-2 My-20 Jn-7 Jn-24
Date (Month-Day)

Figure 2. Accumulative irrigation use by treatments in exp. #1.










Total irrigation ranged from 6.5 to 25.9 inches in Exp-2 (Fig.

3). Rainfall was ignored in the irrigation schedule for this

experiment, however, estimated available water from rainfall in

June was 2.09 inches (0.25 x 8.34). Therefore, total available

water in June from maximum irrigation plus rainfall was 11.09

inches or 0.37 inches/day average. Estimated total average daily

water use during June for tomatoes in Exp-2 at 25, 50, and 75% of

maximum irrigation was 0.15, 0.22, and 0.29 inches/day,

respectively.

Accumulative Irrigation Use (Inches)
30
% of Maximum Irrig.
25 0oo
E 76
20 -ES so
3 265
15

10-




Ap-8 Ap-26 My-16 Jn-15 Jy-15
Date (Month-Day)

Figure 3. Accumulative irrigation use by treatments in exp. #2.



Tensiometer scheduled irrigation and a maximum irrigation rate

of 0.12 inches/day received similar amounts of total irrigation in

Exp-3 (Fig. 4). This was not surprising since average daily

irrigation between 22 May and 29 June for tensiometer scheduled

irrigation was 0.126 inches/day. Tensiometer scheduled irrigation

under a shelter reflects total water demand of tomato plants.










Estimated irrigation use for a 120-day growing period from

tensiometer scheduled irrigation in Exp-3 is 13.8 inches.

Calculations are based on irrigation with 0.06 inches/day for the

first 37 days of growth and 0.14 inches/day for the last 83 days.

The close agreement between Exp-1 and Exp-3 on estimated seasonal

irrigation use confirms that a 120-day tomato crop can be produced

with about 15 inches of drip irrigation in a dry year. The amount

used will vary with length of growing season.


10 Accumulative Irrigation Use (Inches)
Irrigation Schedule
S Tensiomertr
E o.0o-0.00 Inohal/day
E 0.06-0.12 Inches/day



4-


2-


o
Ap-4 Ap-17 My-1 My-11 My-22 Jn-5 Jn-19 Jn-29
Date (Month-Day)

Figure 4. Accumulative irrigation use by treatments in exp. #3.



The relationship between amount of irrigation and total

marketable yield was linear for tomatoes irrigated daily in Exp-2

(Fig. 5). However, regression analysis showed no significant

response of total marketable tomato yield to irrigation applied on

Monday, Wednesday, and Friday of each week. The equation, Y = 16.1

+ 0.125W (r = 0.597, P < 0.01), describes predicted total yield

response to daily irrigation, where Y = tons/acre and W = % of










maximum irrigation. Predicted yield without irrigation was 16.1

tons/acre or 1.15 tons/acre-inch of rainfall during the growing

season. Daily irrigation yield was greater than MWF irrigation

yield at 75% of maximum irrigation (P < 0.05) using a single-

degree-of-freedom comparison.

Total Yield (Tons/Acre)
30
Irrigation Timing
25 Irrig. Applied Dally
Irrig. Applied MWF
20

15-

10 -




6.5 13 19.4 26.9
Total Irrigation Use (Inches)

Figure 5. Total yield by irrigation treatments in exp. #2.


Response of tomatoes in Exp-2 to irrigation was not

significant for harvests 1, 2, and 4 but was strongly expressed in

the third harvest (Fig. 6). The MWF irrigation schedule produced

a positive linear response to irrigation amount at the third

harvest, Y = 6.59 + 0.0402W, r2 = 0.218, P < 0.10), while the daily

irrigation schedule produced a quadratic response (Y = 0.75 +

0.256W-0.00144W2, r2 = 0.629, P < 0.01). Daily irrigation was more

effective than MWF irrigation in Exp-2.












14
Irrigation Timing
12- irrig. Applied Dally
10- Irrig. Applied MWF


8-



4

2


6.5 13 19.4 25.9
Total Irrigation Use (Inches)

Figure 6. Yield of third harvest by irrigation treatments in exp.
#2.


Yield of tomatoes was related to maximum daily irrigation use

(Fig. 7). Maximum yield occurred in each experiment at about 0.25

inches/day maximum irrigation use and higher irrigation rates did

not increase yield.


Yield (Tons/Acre)
40
Irrigation Exper.
-Exp. #l Exp. #2 EExp. #8
30



20



10



1 .23 .08 .15 .23 .3 .06 .12 .24
Maximum Daily Irr. Use (inches/Day)


experiments.









Ratio of yield to irrigation use was highest in Exp-1 with

drip irrigation and lowest with sprinkler irrigation (Fig. 8).

Higher rainfall in Exp-2 caused the ratio to drop rapidly as

irrigation use increased. Actual irrigation efficiency for Exp-2

was 0.48 tons/acre-inch. The ratio of yield to irrigation use was

nearly constant in Exp-3 because irrigation was the only source of

water for plant growth. About 2.5 tons of tomatoes/acre-inch of

irrigation were produced in Exp-3; this is similar to values in

Exp-1 after accounting for rainfall effects. Therefore, 15 inches

of effective drip irrigation would produce about 38 tons of

tomatoes.

Yield:Irrigation Use Ratio (Tons/Ac-in)
4
Irrigation Exper.
I Exp. #1 E Exp. #2 E Exp. #3




2-


1- M



38.76 10.32 26.9 19.43 12.96 6.48 8.98 7.83 4.02
Total Irrigation (Inches)

Figure 8. Ratio of yield:irrigation use versus total irrigation
for all experiments.









CONCLUSIONS

Maximum drip irrigation use by mulched tomatoes was 0.3

inches/day, however, maximum yield was produced with a maximum use

of about 0.25 inches/day. Maximum sprinkler irrigation use was

about 1.0 inch/day. Rainfall and sprinkler irrigation were about

25% or less as effective as drip irrigation for mulched tomatoes.

Maximum yields of tomatoes were obtained with total drip irrigation

use of 15 to 20 inches for a 120-day growing season. Average daily

pan evaporation for Exp-l, which was conducted during a dry year,

was 0.17 inches for the first 50 days of growth and 0.25 inches for

the last 70 days or a season total of 26 inches.



ACKNOWLEDGEMENT

Dr. S. M. Olson supplied plants and equipment for seed bed

preparation for Experiment-2. Audley Manning assisted in

collecting data from all experiments. Mike Bundy assisted with

experiments two and three. Special thanks to Jan Smith for typing

the manuscript.



REFERENCES

1 Davis, D. R., and J. E. Mickelson. 1969. A climatological

summary for the North Florida Experiment Station, Quincy.

Univ. of Fla. IFAS. Mimeo Report NFS 69-1.

2 Steel, R. G. D., and J. H. Torrie. 1960. Principles and

procedures of statistics. McGraw-Hill, New York.










APPENDIX


Table 1.


Conversion of inches of irrigation to gallons per acre
(7260 feet of row).


inches gal/acre inches gal/acre inches gal/acre


0.01 271 0.1 2713 1.0 27127
0.02 543 0.2 5425 2.0 54254
0.03 814 0.3 8138 3.0 81381
0.04 1085 0.4 10851 4.0 108508
0.05 1356 0.5 13564 5.0 135635
0.06 1628 0.6 16276 6.0 162762
0.07 1899 0.7 18989 7.0 189889
0.08 2170 0.8 21702 8.0 217016
0.09 2441 0.9 24414 9.0 244143




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