• TABLE OF CONTENTS
HIDE
 Copyright
 Introduction
 What is trickle irrigation
 How does trickle irrigation...
 Equipment and installation
 Fertilizing possibilities
 Frost protection
 Other advantages of trickle...
 Possible problems
 Conclusions














Group Title: AREC-H research report - Agricultural Research and Education Center-Homestead ; SB-73-2
Title: Trickle Irrigation
CITATION PAGE IMAGE ZOOMABLE
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00067837/00001
 Material Information
Title: Trickle Irrigation
Series Title: Homestead AREC research report
Physical Description: 4 leaves : ; 28 cm.
Language: English
Creator: Malo, Simâon E
Agricultural Research and Education Center, Homestead
Publisher: University of Florida, Institute of Food and Agricultural sciences, Agricultural Research and Education Center
Place of Publication: Homestead Fla
Publication Date: 1973
 Subjects
Subject: Microirrigation -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
 Notes
Statement of Responsibility: Simon Malo E.
General Note: "March 28, 1973"
 Record Information
Bibliographic ID: UF00067837
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 72440161

Table of Contents
    Copyright
        Copyright
    Introduction
        Page 1
    What is trickle irrigation
        Page 1
    How does trickle irrigation work
        Page 1
    Equipment and installation
        Page 2
    Fertilizing possibilities
        Page 2
    Frost protection
        Page 3
    Other advantages of trickle irrigation
        Page 3
    Possible problems
        Page 3
    Conclusions
        Page 4
Full Text





HISTORIC NOTE


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
(EDIS)

site maintained by the Florida
Cooperative Extension Service.






Copyright 2005, Board of Trustees, University
of Florida




a-- 4


Homestead AREC Research Report SB73-2 March 28, 1973


"Trickle Irrigation"


Simon E. Malo
ss ciate Horticulturist
SeRUni ersity of Florida
S ute of Fo d and Agricultural Sciences
Agricultural Re earch and Education Center
\ 1gR2 73 Homestead


S. i. F\od production
The concept f irrigation has been known for many decades; however, recent
progress with plastic water conducting equipment is mainly responsible for its pre-
sent successful application to horticultural crops. Of course credit should also go
to Israeli and Australian agriculturists and engineers who took the concept from the
greenhouse stage and applied it to field conditions. These countries are located in
the warm latitudes, with very limited water resources and the absence of abundant
rainfall. These handicaps have been the driving force to innovate and search for
more economic and efficient means of irrigation. Today practically all horticultural
crops depend upon irrigation and the trickle concept has become a valuable tool for
increasing production and insuring adequate yields.


What Is Trickle Irrigation?

Also called "daily flow" or "drip", trickle irrigation consists of supplying plants
with constant moisture at a low delivery rate, thus eliminating fluctuation in the
soil moisture level and the consequent water stress which is apparently responsible
for damaging plant rootlets, reducing their capacity to take up water and nutrients.
Moisture levels are maintained somewhere between saturation and field capacity. At
present there are a variety of methods for accomplishing this and all of them work
fairly well. Some of them have obvious advantages over the other ones, but none of
them are perfect. New ideas and refinements are constantly appearing, their develop-
ment stimulated by the present success of the trickle irrigation concept.


How Does Trickle Irrigation Work?

Very low rates of water are applied to the soil at frequent intervals to replace what
is lost by evapotranspirationn." This term combines the amount of water removed from
the soil surface by evaporation and what is lost through the leaves of the plant by
transpiration. These two phenomena are responsible for lowering the moisture avail-
able to plants in the soil. Approximate evaporation averages can be obtained from
metereological records but daily transpiration figures are unavailable for most crops
under changing climatic conditions. Since we need to know precisely when and how
much to irrigate to maintain an adequate moisture level, and since we cannot get this
information from evaporation figures, it is necessary to use several stationary
'tensiometers" for this purpose. A tensiometer is an instrument designed for measur-
ing soil moisture conditions, and can be used to determine when water should be
applied.


SB73-2
450 copies




a-- 4


Homestead AREC Research Report SB73-2 March 28, 1973


"Trickle Irrigation"


Simon E. Malo
ss ciate Horticulturist
SeRUni ersity of Florida
S ute of Fo d and Agricultural Sciences
Agricultural Re earch and Education Center
\ 1gR2 73 Homestead


S. i. F\od production
The concept f irrigation has been known for many decades; however, recent
progress with plastic water conducting equipment is mainly responsible for its pre-
sent successful application to horticultural crops. Of course credit should also go
to Israeli and Australian agriculturists and engineers who took the concept from the
greenhouse stage and applied it to field conditions. These countries are located in
the warm latitudes, with very limited water resources and the absence of abundant
rainfall. These handicaps have been the driving force to innovate and search for
more economic and efficient means of irrigation. Today practically all horticultural
crops depend upon irrigation and the trickle concept has become a valuable tool for
increasing production and insuring adequate yields.


What Is Trickle Irrigation?

Also called "daily flow" or "drip", trickle irrigation consists of supplying plants
with constant moisture at a low delivery rate, thus eliminating fluctuation in the
soil moisture level and the consequent water stress which is apparently responsible
for damaging plant rootlets, reducing their capacity to take up water and nutrients.
Moisture levels are maintained somewhere between saturation and field capacity. At
present there are a variety of methods for accomplishing this and all of them work
fairly well. Some of them have obvious advantages over the other ones, but none of
them are perfect. New ideas and refinements are constantly appearing, their develop-
ment stimulated by the present success of the trickle irrigation concept.


How Does Trickle Irrigation Work?

Very low rates of water are applied to the soil at frequent intervals to replace what
is lost by evapotranspirationn." This term combines the amount of water removed from
the soil surface by evaporation and what is lost through the leaves of the plant by
transpiration. These two phenomena are responsible for lowering the moisture avail-
able to plants in the soil. Approximate evaporation averages can be obtained from
metereological records but daily transpiration figures are unavailable for most crops
under changing climatic conditions. Since we need to know precisely when and how
much to irrigate to maintain an adequate moisture level, and since we cannot get this
information from evaporation figures, it is necessary to use several stationary
'tensiometers" for this purpose. A tensiometer is an instrument designed for measur-
ing soil moisture conditions, and can be used to determine when water should be
applied.


SB73-2
450 copies




a-- 4


Homestead AREC Research Report SB73-2 March 28, 1973


"Trickle Irrigation"


Simon E. Malo
ss ciate Horticulturist
SeRUni ersity of Florida
S ute of Fo d and Agricultural Sciences
Agricultural Re earch and Education Center
\ 1gR2 73 Homestead


S. i. F\od production
The concept f irrigation has been known for many decades; however, recent
progress with plastic water conducting equipment is mainly responsible for its pre-
sent successful application to horticultural crops. Of course credit should also go
to Israeli and Australian agriculturists and engineers who took the concept from the
greenhouse stage and applied it to field conditions. These countries are located in
the warm latitudes, with very limited water resources and the absence of abundant
rainfall. These handicaps have been the driving force to innovate and search for
more economic and efficient means of irrigation. Today practically all horticultural
crops depend upon irrigation and the trickle concept has become a valuable tool for
increasing production and insuring adequate yields.


What Is Trickle Irrigation?

Also called "daily flow" or "drip", trickle irrigation consists of supplying plants
with constant moisture at a low delivery rate, thus eliminating fluctuation in the
soil moisture level and the consequent water stress which is apparently responsible
for damaging plant rootlets, reducing their capacity to take up water and nutrients.
Moisture levels are maintained somewhere between saturation and field capacity. At
present there are a variety of methods for accomplishing this and all of them work
fairly well. Some of them have obvious advantages over the other ones, but none of
them are perfect. New ideas and refinements are constantly appearing, their develop-
ment stimulated by the present success of the trickle irrigation concept.


How Does Trickle Irrigation Work?

Very low rates of water are applied to the soil at frequent intervals to replace what
is lost by evapotranspirationn." This term combines the amount of water removed from
the soil surface by evaporation and what is lost through the leaves of the plant by
transpiration. These two phenomena are responsible for lowering the moisture avail-
able to plants in the soil. Approximate evaporation averages can be obtained from
metereological records but daily transpiration figures are unavailable for most crops
under changing climatic conditions. Since we need to know precisely when and how
much to irrigate to maintain an adequate moisture level, and since we cannot get this
information from evaporation figures, it is necessary to use several stationary
'tensiometers" for this purpose. A tensiometer is an instrument designed for measur-
ing soil moisture conditions, and can be used to determine when water should be
applied.


SB73-2
450 copies







-2-

* Research indicates that it is possible to satisfy a plant's water requirement by
supplying water to only a part of the total root system.


Equipment And Installation

Since the rate of application necessary is very small and the pressure required is
seldom higher than one atmosphere (approximately 15.0 psi) the equipment required by
trickle irrigation is relatively simple and inexpensive. Generally we need a pump
connected to a water source, a good filter, pressure gauges and valves, PVC pipes and
flexible polyethylene tubing for the laterals to conduct water to the emitters (also
called drippers, nozzles, etc.) which are designed to bring the pressure down from
15.0 psi to zero and to deliver water at a constant flow. In addition to this, as
mentioned before, it is essential to have a certain number of tensiometers to measure
accurately the moisture content of the soil at a desired depth. A suitable tank for
fertilizer can be added to this list, if we want to "fertigate" through the water
lines.

The Pump: Since the desired gpm is very small compared to sprinkler irrigation, and
the pressure not higher than 15.0 psi, we can use small centrifugal pumps, either
electrical or with gas engines, which can be easily adjusted to provide a specified
constant pressure. Electrical pumps have the advantage because of their versatility
and reliability and should be considered whenever possible. Preliminary studies have
shown that a 3-hp (single phase) electrical pump is sufficient to irrigate a 20 acre
orchard.

SFiltration: A good filter is an indispensable integral part of a trickle irrigation
installation which we cannot afford to leave out. The small orifices of the emitters
can be readily plugged up by impurities, so it is essential to have clean water. The
filter is an insurance against future difficulties. It should be located so that all
the water and any additives pass through it before reaching the emitters. Filters
with screens of 200-400 mesh should be adequate. Filters finer than this clog up
with chemicals or sediment and are not necessary.


Fertilizing Possibilities

For orchards in the Homestead area particularly those planted by cross-trenching, the
possibilities are excellent for using trickle irrigation to deliver fertilizer to the
plant. Dissolved mixtures of soluble chemicals can be either injected or more simply
absorbed into the water line by locating the intake valve to take advantage of the
pump's suction. Slow delivery of nutrients insures even distribution of the materials
throughout the orchard. In this manner we deliver precise amounts of nutrients and
discharge them in areas where rootlets are abundant because of the presence of an
optimum soil moisture. The proper application of chelates, particularly those that
are expensive and difficult to handle such as Sequestrene 138, is perhaps one of the
greatest advantages to the Homestead area where the incidence of iron chlorosis is so
high. A surfactant should be used to facilitate dissolution and the wetting of Seq.
138. The material is only partly soluble and needs continuous agitation to keep it
from settling to the bottom of the container.


., -i







-2-

* Research indicates that it is possible to satisfy a plant's water requirement by
supplying water to only a part of the total root system.


Equipment And Installation

Since the rate of application necessary is very small and the pressure required is
seldom higher than one atmosphere (approximately 15.0 psi) the equipment required by
trickle irrigation is relatively simple and inexpensive. Generally we need a pump
connected to a water source, a good filter, pressure gauges and valves, PVC pipes and
flexible polyethylene tubing for the laterals to conduct water to the emitters (also
called drippers, nozzles, etc.) which are designed to bring the pressure down from
15.0 psi to zero and to deliver water at a constant flow. In addition to this, as
mentioned before, it is essential to have a certain number of tensiometers to measure
accurately the moisture content of the soil at a desired depth. A suitable tank for
fertilizer can be added to this list, if we want to "fertigate" through the water
lines.

The Pump: Since the desired gpm is very small compared to sprinkler irrigation, and
the pressure not higher than 15.0 psi, we can use small centrifugal pumps, either
electrical or with gas engines, which can be easily adjusted to provide a specified
constant pressure. Electrical pumps have the advantage because of their versatility
and reliability and should be considered whenever possible. Preliminary studies have
shown that a 3-hp (single phase) electrical pump is sufficient to irrigate a 20 acre
orchard.

SFiltration: A good filter is an indispensable integral part of a trickle irrigation
installation which we cannot afford to leave out. The small orifices of the emitters
can be readily plugged up by impurities, so it is essential to have clean water. The
filter is an insurance against future difficulties. It should be located so that all
the water and any additives pass through it before reaching the emitters. Filters
with screens of 200-400 mesh should be adequate. Filters finer than this clog up
with chemicals or sediment and are not necessary.


Fertilizing Possibilities

For orchards in the Homestead area particularly those planted by cross-trenching, the
possibilities are excellent for using trickle irrigation to deliver fertilizer to the
plant. Dissolved mixtures of soluble chemicals can be either injected or more simply
absorbed into the water line by locating the intake valve to take advantage of the
pump's suction. Slow delivery of nutrients insures even distribution of the materials
throughout the orchard. In this manner we deliver precise amounts of nutrients and
discharge them in areas where rootlets are abundant because of the presence of an
optimum soil moisture. The proper application of chelates, particularly those that
are expensive and difficult to handle such as Sequestrene 138, is perhaps one of the
greatest advantages to the Homestead area where the incidence of iron chlorosis is so
high. A surfactant should be used to facilitate dissolution and the wetting of Seq.
138. The material is only partly soluble and needs continuous agitation to keep it
from settling to the bottom of the container.


., -i








Frost Protection

* Trickle irrigation, in contrast to sprinkler irrigation, does not provide frost pro-
tection. However, if clean cultivation or wide banding with herbicides is used, the
clean, moist ground should give a certain measure of frost protection through in-
creased heat radiation.


Other Advantages Of Trickle Irrigation

In addition to the advantages already discussed, the following are potential benefits:

1. Labor saving: If a system is properly installed, it will require only a small
amount of time for subsequent inspection and maintenance. For automatic opera-
tion, the system can be connected to a time clock or a mechanism which starts
the pump when the soil moisture reaches the desired minimum.

2. Water conservation: Due to almost negligible evaporation and percolation losses,
trickle irrigation uses comparatively small amounts of water. This is a distinct
advantage particularly for areas where agriculture competes with urban areas for
good quality water.

3. Salinity in the water: Although it does not concern us directly in South Florida,
trickle irrigation lessens the danger to plants caused by salt in the irrigation
water.

4. Increased yields and young tree growth: Since the root zone remains moist con-
stantly, young trees particularly replants make excellent growth, and fruit pro-
duction increases in established orchards.

5. Weed growth reduced: By wetting only the area around an emitter, weed growth is
reduced considerably particularly during the dry season of the year.

6. Cost of operation and installation: Perhaps the most attractive feature is the
reduced cost of operation and installation. It is estimated that the price of
installation, for the Homestead area, should not exceed $350.00 per acre. Several
systems have been installed in this area at considerable lower prices than this.
In addition, the use of small pumps reduces the operation cost of irrigation.


Possible Problems

Observations after a year of operating a trickle irrigation experiment at this Center
have taught us that the grower should be aware of the following possible problems:

1. Algae: Green algae growth around the emitters could become a very serious pro-
blem by obstructing the water outlets and slowing down the outflow of water. It
has been reported that algal growth may be prevented by passing a 3 ppm solution
of copper sulfate (3.0 lbs in 100,000 gallons) through the water lines. If the
emitters are already covered with green slime a spray containing a 5% solution of
copper sulfate should get rid of the algae in a few days.

2. Calcium carbonate and iron oxide deposits: After one year this problem has not
become serious in our plots but the potential for plugging emitters still remains.
Chemicals which dissolve these accumulations have been tested successfully but
additional work is needed before theycan be recommended.


<*.s-- *








Frost Protection

* Trickle irrigation, in contrast to sprinkler irrigation, does not provide frost pro-
tection. However, if clean cultivation or wide banding with herbicides is used, the
clean, moist ground should give a certain measure of frost protection through in-
creased heat radiation.


Other Advantages Of Trickle Irrigation

In addition to the advantages already discussed, the following are potential benefits:

1. Labor saving: If a system is properly installed, it will require only a small
amount of time for subsequent inspection and maintenance. For automatic opera-
tion, the system can be connected to a time clock or a mechanism which starts
the pump when the soil moisture reaches the desired minimum.

2. Water conservation: Due to almost negligible evaporation and percolation losses,
trickle irrigation uses comparatively small amounts of water. This is a distinct
advantage particularly for areas where agriculture competes with urban areas for
good quality water.

3. Salinity in the water: Although it does not concern us directly in South Florida,
trickle irrigation lessens the danger to plants caused by salt in the irrigation
water.

4. Increased yields and young tree growth: Since the root zone remains moist con-
stantly, young trees particularly replants make excellent growth, and fruit pro-
duction increases in established orchards.

5. Weed growth reduced: By wetting only the area around an emitter, weed growth is
reduced considerably particularly during the dry season of the year.

6. Cost of operation and installation: Perhaps the most attractive feature is the
reduced cost of operation and installation. It is estimated that the price of
installation, for the Homestead area, should not exceed $350.00 per acre. Several
systems have been installed in this area at considerable lower prices than this.
In addition, the use of small pumps reduces the operation cost of irrigation.


Possible Problems

Observations after a year of operating a trickle irrigation experiment at this Center
have taught us that the grower should be aware of the following possible problems:

1. Algae: Green algae growth around the emitters could become a very serious pro-
blem by obstructing the water outlets and slowing down the outflow of water. It
has been reported that algal growth may be prevented by passing a 3 ppm solution
of copper sulfate (3.0 lbs in 100,000 gallons) through the water lines. If the
emitters are already covered with green slime a spray containing a 5% solution of
copper sulfate should get rid of the algae in a few days.

2. Calcium carbonate and iron oxide deposits: After one year this problem has not
become serious in our plots but the potential for plugging emitters still remains.
Chemicals which dissolve these accumulations have been tested successfully but
additional work is needed before theycan be recommended.


<*.s-- *








Frost Protection

* Trickle irrigation, in contrast to sprinkler irrigation, does not provide frost pro-
tection. However, if clean cultivation or wide banding with herbicides is used, the
clean, moist ground should give a certain measure of frost protection through in-
creased heat radiation.


Other Advantages Of Trickle Irrigation

In addition to the advantages already discussed, the following are potential benefits:

1. Labor saving: If a system is properly installed, it will require only a small
amount of time for subsequent inspection and maintenance. For automatic opera-
tion, the system can be connected to a time clock or a mechanism which starts
the pump when the soil moisture reaches the desired minimum.

2. Water conservation: Due to almost negligible evaporation and percolation losses,
trickle irrigation uses comparatively small amounts of water. This is a distinct
advantage particularly for areas where agriculture competes with urban areas for
good quality water.

3. Salinity in the water: Although it does not concern us directly in South Florida,
trickle irrigation lessens the danger to plants caused by salt in the irrigation
water.

4. Increased yields and young tree growth: Since the root zone remains moist con-
stantly, young trees particularly replants make excellent growth, and fruit pro-
duction increases in established orchards.

5. Weed growth reduced: By wetting only the area around an emitter, weed growth is
reduced considerably particularly during the dry season of the year.

6. Cost of operation and installation: Perhaps the most attractive feature is the
reduced cost of operation and installation. It is estimated that the price of
installation, for the Homestead area, should not exceed $350.00 per acre. Several
systems have been installed in this area at considerable lower prices than this.
In addition, the use of small pumps reduces the operation cost of irrigation.


Possible Problems

Observations after a year of operating a trickle irrigation experiment at this Center
have taught us that the grower should be aware of the following possible problems:

1. Algae: Green algae growth around the emitters could become a very serious pro-
blem by obstructing the water outlets and slowing down the outflow of water. It
has been reported that algal growth may be prevented by passing a 3 ppm solution
of copper sulfate (3.0 lbs in 100,000 gallons) through the water lines. If the
emitters are already covered with green slime a spray containing a 5% solution of
copper sulfate should get rid of the algae in a few days.

2. Calcium carbonate and iron oxide deposits: After one year this problem has not
become serious in our plots but the potential for plugging emitters still remains.
Chemicals which dissolve these accumulations have been tested successfully but
additional work is needed before theycan be recommended.


<*.s-- *




..-


3. Too much soil moisture: Without the use of tensiometers it is practically impos-
sible to estimate the proper amount of water needed, and when in doubt the tend-
ency is to use too much. Not only is this wasteful but it might result in the
development of soil borne fungi which in the case of Phytophthora cinnamon in
avocado may be fatal to the tree.


Conclusions

Trickle irrigation appears to be suited for cross-trenched orchards in the Homestead
area. The advantages and potential difficulties are currently under investigation at
this Center. Thus far, the possibilities appear to outnumber the potential disadvan-
tages. Interested growers should obtain all the available information on the instal-
lation and operation of trickle irrigation systems before getting heavily involved
with this new irrigation concept. The operation of tensiometers is sometimes tricky
and their proper handling and interpretation needs experience; however their use is
essential for the proper operation of trickle irrigation.




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