Group Title: Research report - Bradenton Agricultural Research & Education Center - GC1979-13
Title: Considerations in calculating and reporting water application rates for drip irrigated lands
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00067726/00001
 Material Information
Title: Considerations in calculating and reporting water application rates for drip irrigated lands
Series Title: Bradenton AREC research report
Physical Description: 3 leaves : ; 28 cm.
Language: English
Creator: Csizinszky, Alexander Anthony, 1933-
Agricultural Research & Education Center (Bradenton, Fla.)
Publisher: Agricultural Research & Education Center, IFAS, University of Florida
Place of Publication: Bradenton Fla
Publication Date: 1979
Subject: Microirrigation -- Florida   ( lcsh )
Soil permeability -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
Statement of Responsibility: Alexander A. Csizinszky.
General Note: Caption title.
General Note: "August 1979."
Funding: Florida Historical Agriculture and Rural Life
 Record Information
Bibliographic ID: UF00067726
Volume ID: VID00001
Source Institution: Marston Science Library, George A. Smathers Libraries, University of Florida
Holding Location: Florida Agricultural Experiment Station, Florida Cooperative Extension Service, Florida Department of Agriculture and Consumer Services, and the Engineering and Industrial Experiment Station; Institute for Food and Agricultural Services (IFAS), University of Florida
Rights Management: All rights reserved, Board of Trustees of the University of Florida
Resource Identifier: oclc - 73155546

Table of Contents
        Page 1
        Page 2
        Page 3
Full Text


The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
Electronic Data Information Source

site maintained by the Florida
Cooperative Extension Service.

Copyright 2005, Board of Trustees, University
of Florida

S 0 Agricultural Research & Education Center
/76 IFAS, University of Florida
( JC, Bradenton, Florida
Bradenton AREC Research Report GC1979-13 -u'uc 1 79R/ RApY

Alexander A. Csizinszky I.F.A.S. Univ. of Florida

In the drip (or trickle) irrigation system, water is applied near the plant
root zone for maximum beneficial effect. On Myakka fine sandy soils with a spodic
layer at 2-3 ft (61 to 91 cm) below the surface, the soil in the shoulder region of
the raised plant beds under the plastic mulch and between the plant beds to a depth
of 2-3 inches (5-7.5 cm) is dry in the drip irrigated lands. During periods of little
or no rainfall, the soil water table is low. This is in direct contrast with seep
irrigated lands where the maintenance of the soil water table throughout the growing
season at approximately 18 in (46 cm) below the surface of the raised beds is essen-
tial for optimum plant growth. In seep irrigation water moves laterally from the
irrigation ditches, then vertically under the plastic mulch to the soil surface.
With drip irrigation there is a very limited horizontal movement of water in the
plant beds and only an approximately 3-5 in. (7.5-13 cm) wide band of soil is mois-
tened above the buried drip tube under the plastic mulch. Otherwise the top 0-2 in.
(0-5 cm) soil layer in the plant bed has a low moisture content.
In southwest Florida heavy rainfalls may occur at any time during the growing
season. Thus, growing .te plants on raised beds and the formation and maintenance
of drainage furrows tq facilitate the rapid surface runoff of water from the culti-
vated lands is very important even in drip irrigated lands. Drainage furrows or
ditches occupy a certain percentage of the land which cannot be used for plant growth.

The area under plastic mulch on a given land will depend on the number of drain-
age ditches formed, distance between plant rows, and the width of the plant bed.
Number of plants per acre (or ha) depends on the area under plastic mulch and on
the planting distance within the rows.
For example, at the AREC-Bradenton the drip irrigated land is 300 ft (91.5 m)
long and the distance between the centers of two lateral drainage ditches is 41.5 ft
(12.6 m). Rows are formed with 4.5 ft (1.," m) cc~-rs, 7 rows per land, with a
total length of 2,100 row ft (640 row m) and occupy 76% of the area. The width of
the plant bed under the plastic mulch, measured across the top is 2.5 ft (76 cm).
The area covered by plastic mulch is 5250 sq ft (488 m2) or 42% of the total land.
Plants are set at various within-row planting distances. In this paper 2 ft (61 cm)
planting distance within the rows are used, which gives a total of 1050 plants.
Frequency and duration of water flow is regulated by time clocks. Volume of flow
is constant at a rate of 3.5 gallons per minute (gpm) or 13.25 liters per minute
(Lpm) regulated by a Dole valve at 3.5 lb per sq in (0.246 kg/cm ) pressure. In the
following example the total flow time of irrigation water was 12,000 minutes (min)
during a 100 day growing season for an area of 12,450 sq ft (300 ft x 41.5 ft), or
1,144 m2. The question is presented: How much water was applied to the land in acre
inches (A in.)? The most convenient method is to calculate the amount of irrigation
water on the basis of the total land area involved which also includes the drainage
ditches. This allows a direct comparison with the amount of water applied for the
crop in a seep irrigated system.

Using the U. S. system of measurement [1 acre (A) = 43,560 sq ft; 1 A inch =
27,154 gal]:

A in. of water applied for the season flow rate x flow time x 43,560 sq ft
irrigated area x 27,154 gal
3.5 gpm x 12,000 min x 43,560 sq ft. 5.41 A in. per season.
= 1,5 sq ftx21 gl = 5.41 A in. per season.
12,450 sq ft x 27,154 gal

In gallons: 5.41 A in. x 27,154 gal = 146,903 gallons of water for 1 A.
Using the metric system of measurement (1 ha = 10,000 m2; 1 m3 = 1000 L and the
area irrigated is 1,144 m2):
Liters of water per m2 per season (L/m2 1325 L x 12000 min = 39 L/2 per
1,144 m=
season. 2 2
3 13.9 L/m x 10,000 m2
In m /ha = 139 ,m x 10,000 m = 1,390 m3 of water per ha per season.
1,000 L
Calculating and reporting the water applied with the drip irrigation system
on a total area basis does not give realistic data for the reader on the amount of
water applied for the plants during the growing season. Water is applied under the
plastic mulch near the root zone where it is most efficiently used by the plants.
Water applied with the drip system is more precisely expressed on the basis of 1)
net row acre, or 2) area under plastic mulch, or 3) per 100 row ft (100 row m), or
4) on a per plant basis. The method of reporting would not alter the total amount
of water applied for the total area (broadcast acre) as may be seen on Table 1.

It is obvious that no single method of reporting the water applied would satis-
fy all the information required by growers, researchers and water regulatory author-
ities. Two of the data from Table 1 which provide the most useful information for
the readers are the water applied on a total area basis (A in. or m3/ha) and on a
per plant basis (gallons or liters per plant). By providing the other parameters
of the experimental conditions in the text, e.g., net row acre (net row hectare),
number of plants per acre (or per ha), readers would be able to make comparisons
for their specific conditions.

During the growing season people working with drip irrigation want to know how
long the water should run through the drip tubes to deliver the required amount of
water for the crop. For example: we wish to apply 0.0541 A in. of water (1.39
L/m2) through a valve delivering 3.5 gpm (13.25 L/min) of water to an area of
12,450 sq ft (1144 m4). How many minutes does it take to deliver this amount of
In U. S. system:
Flow time in m s A in. of water required x area irrigated x gal/A in.
Flow time in minutes flow rate x 43,560 sq ft.
= 0.0541 A in. x 12,450 sq ft x 27,154 gal = 120 minutes flow time.
3.5 gpm x 43,560 sq ft.
In Metric system:
Flow time water required (L/m2) x area irrigated (m2) 1.39 L/m2 x 1,144 m
flow rate in minutes 13.15 L/min.

= 120 minutes flow time.


Table 1. Amount of water applied during a 100 day long season by drip irrigation.

U. S. System1

Calculation based on:

Broadcast acre, 43,560 sq ft/A

Net row acre, 33,106 sq ft/A

Area under plastic mulch cover, 18,390 sq ft/A

Per 100 row ft, 7,357 row ft/A

Per plant, 3,678 plants/A

Metric System2

Per m2 of total area, 10,000 m2/ha

Net row per ha, 7,600 m2/ha

Area under plastic mulch cover, 4216 m2/ha

Per 100 row m, 5,547 row m/ha

Per plant, 9,093 plants/ha






Irrigation water
per season

gal/sq ft or 5.4

gal/sq ft or 5.4

gal/sq ft or 5.4

gal or 5.4

gal or 5.4

139.00 L/m2

182.89 L/m2

329.70 L/m2

25,059 L

152.86 L





or 1,390 m3

or 1,390 m3

or 1,390 m3

or 1,390 m3

or 1,390 m3






Flow rate of water 3.5 gpm for 12,450 sq ft, total

2Flow rate of water 13.25 L/min for 1,144 m2, total

flow time 12,000 minutes.

flow time 12,000 minutes.

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