Citation
Calibration of fertilizer injectors for agricultural irrigation systems

Material Information

Title:
Calibration of fertilizer injectors for agricultural irrigation systems
Series Title:
Circular Florida Cooperative Extension Service
Creator:
Smajstrla, A. G ( Allen George )
Haman, D. Z ( Dorota Z )
Zazueta, F. S ( Fedro S )
Place of Publication:
Gainesville Fla
Publisher:
Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida
Publication Date:
Language:
English
Physical Description:
4 p. : ; 28 cm.

Subjects

Subjects / Keywords:
Fertilizers -- Application ( lcsh )
Irrigation ( lcsh )
Genre:
non-fiction ( marcgt )

Notes

General Note:
Caption title.
General Note:
"January 1992."
Statement of Responsibility:
A.G. Smajstrla, D.Z. Haman and F.S. Zazueta.

Record Information

Source Institution:
University of Florida
Holding Location:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
AAA6893 ( LTQF )
AJC0393 ( LTUF )
25526205 ( OCLC )
021930425 ( AlephBibNum )

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c January 1992 Circular 1033


'........* INS T U T E OF FOOD A N D A G R IC U L T U R AL S.C IEN C E-S


Calibration of Fertilizer Injectors :

for Agricultural Irrigation Systems


A. G. Smajstrla, D. Z. Haman and F. S. Zazueta*

Florida Cooperative Extension Service / Institute of Food and Agricultural Sciences / University of Florida / John T. Woeste, Dean


Fertilizer application through an irrigation sys-
tem is called "fertigation". Fertigation is practiced
for several reasons the primary reasons are
lower application costs and greater production re-
sponses. It is normally less expensive to apply fer-
tilizers with irrigation water than by other meth-
ods, especially if several applications are required
during the growing season. Also, for many Florida
crops, growth and yields have been increased when
fertigation was used to maintain optimum nutrient
levels at critical crop growth stages.

Other reasons for the popularity of fertigation
include: (1) the ability to make prescription applica-
tions of fertilizers; that is, to apply them precisely
when needed and only in the amounts needed, thus
maximizing their effectiveness, (2) a reduction in
environmental pollution because fertilizers can be
applied only in the amounts needed and thus large
quantities are not subject to leaching loss if heavy
rainfalls follow conventional applications, and (3) a
possible reduction in the total volume of fertilizers
applied because leaching losses are minimized.

Growers should only inject water soluble fertiliz-
ers or fertilizer suspensions that are compatible
with their irrigation system and crop production
system. Because they are potentially corrosive,
fertilizers should be flushed from the irrigation sys-
tem after each application. Fertilizer solutions
should always be injected before (upstream of) the
filters in microirrigation systems. The compatibil-
ity of fertilizer solutions with the irrigation water
and with any other chemicals being injected should
be tested to avoid the formation of chemical precipi-
tates in the irrigation system. IFAS production
guides should be consulted for the specific crop be-
ing produced to obtain recommendations for chemi-
cal formulations, fertigation rates and schedules.

*Professor, and associate professors, Agricultural Engineering
Department, University of Florida, FL 32611.


Calibration of fertilizer injection
systems
Each method of fertilizer injection must be cali-
brated by the user. Calibration procedures vary
depending upon the injection method used and
the specific design of the injection equipment.
In all cases, however, the user must verify that the
manufacturer's calibration or the method being
used is correct by using a chemical flow meter
which is accurate in the flow range of gallons per
hour (or other rate being injected), or by measuring
the injection rate volumetrically.

Chemical flow meters
Flow meters are available which can be used to
directly measure the chemical flow rate while the
injection system is operating under field conditions.
Meters can often be mounted on the low pressure
(suction) side of injection pumps.

Caution: If a chemical flow meter is used on the
high pressure side of an injector, be certain that the
flow meter is rated for the pressure being used be-
fore installing it in that position. Failure to use a
properly installed, adequately pressure-rated meter
may cause it to be damaged, and it may be hazard-
ous to individuals working in the area.

Volumetric flow rate measurement
To measure flow rates volumetrically, a con-
tainer of known volume (such as a graduated cylin-
der) and an accurate timer (such as a stopwatch or
a watch with second hand) are needed. Measure
the time required to fill the container. Then calcu-
late the flow rate as the volume per time, typically
in units of gallons per hour (gal/hr or gph).

For example, assume that a 100 ml graduated
cylinder and stopwatch were used to measure injec-
tion rates. Assume that 92 ml of fertilizer solution








was collected in 4 minutes, 31 seconds. To convert
ml to gal, divide by 3,785 ml/gal. Then 92 ml = 92/
3,785 = 0.0243 gal. To convert seconds to hours,
divide by 3,600 sec/hr. Then 4 min, 31 sec = 271
sec, and 271/3,600 = 0.0753 hr. Finally, 0.0243 gal/
0.0753 hr = 0.32 gal/hr.

For many injection methods, the injection pump
calibration will change depending upon the pres-
sure in the irrigation system. The actual injection
rate will be less when injecting against pressure.
Therefore, the above procedure can be used only as
a first approximation of the final calibration set-
ting, and the calibration will need to be finalized in
the field during fertilizer injection into the irriga-
tion system.

Finalizing calibrations in the field
To finalize the calibration of an injector, measure
the rate of fertilizer depletion from the storage
tank. Install a small graduated supply tank if the
bulk storage tank is not graduated for accurate
measurement of volumes injected.

It is a good idea to inject fertilizers from a small
graduated supply tank rather than to pump di-
rectly from a large bulk storage tank. The small
tank should be sized to contain the fertilizer solu-
tion needed for one application, and only the
required amount of fertilizer solution should be
placed in the small tank before the irrigation dur-
ing which it will be injected. This procedure can
improve the effectiveness of fertilizer injection be-
cause (1) only the amount of fertilizer in the small
supply tank can be injected during irrigation, thus
preventing excess applications from accidentally
being made, (2) the amount of fertilizer injected can
easily and accurately be read if the supply tank is
relatively small and has graduations permanently
marked on it, and (3) only the fertilizer in the small
tank will be diluted if backflow from the irrigation
system occurs because of failure of the injection
pump and backflow prevention system.

For injection methods which use a suction tubing
between the injection pump and the supply tank,
the injection rate can be measured with a chemical
flow meter or by connecting the tubing to a gradu-
ated cylinder. Measurements should be made
while the injector is operating under normal condi-
tions, including normal injection rates and normal
irrigation system operating pressures. Then ad-
justments in the injection rate can be made as the
injection system operates.


Calculating fertilizer injection
rates
For all methods of injection, the required fertil-
izer injection rate must be known. The required
injection rate can be calculated from the following
equations for solid set (including sprinkler and mi-
cro systems), center pivot and traveling gun irriga-
tion systems.

Solid set irrigation systems
Solid set systems include sprinkler and micro
(drip and microsprinkler) irrigation systems. For
solid set irrigation systems, the fertilizer injection
rate in gallons per hour (gph) is calculated from:

Rate=[ 100 A F ]/[ P H W] (1)
where Rate = fertilizer injection rate (gph),
A = area to be irrigated (ac),
F = fertilizer amount to be applied per acre (lb/ac),
P = fertilizer fraction, percent of fertilizer per gal-
lon of fluid injected (%),
H = fertilizer application time (hr), and
W= weight of fertilizer solution (lb/gal).

As an example of the use of Equation (1), assume
that 20 lb of nitrogen (N) must be applied per acre
on a 5-acre citrus nursery using sprinkler irriga-
tion. The fertilizer to be used is a liquid solution of
Ammonium Nitrate (21% N; 10.73 lb/gal)1. The
normal irrigation cycle is 2 hr, and fertilizer injec-
tion begins immediately after the system has
reached normal operating pressure. Fertilizer will
be injected for 1.5 hr, leaving almost 0.5 hr to flush
the fertilizer from the irrigation system and off of
the plants. Using equation (1):

Rate = [100 5 ac 20 lb/ac]
[21% 1.5 hr 10.73 lb/gall
Rate = 29.6 gph

Thus, the required 20 lb of N can be applied per
acre by injecting 29.6 gal of Ammonium Nitrate per
hour for the 1.5 hr injection time. The total volume
to be injected would be 29.6 gal/hr times 1.5 hr =
44.4 gal.


'Because liquid fertilizer solutions are often custom mixed, the
nutrient concentrations and weight of the fertilizer solution
must be obtained from the fertilizer supplier. Common values
are used in this publication.








If the above 20 lb of N per acre must be applied
to a 5-acre citrus grove that is irrigated with a
microsprinkler system, Equation (1) can still be
used. Assume that the micro system is operated for
6 hr at each irrigation and that fertilizer is injected
for 4 hr. Fertilizer injection begins immediately
after the system has reached normal operating
pressure, leaving almost 2 hr to flush the fertilizer
from the irrigation system. Then:

Rate = [100 5 ac 20 lb/ac]
[21% 4 hr 10.73 lb/gal]
Rate = 11.1 gph

Thus, the required 20 lb of N can be applied per
acre by injecting 11.1 gal of Ammonium Nitrate per
hour for the 4 hr injection time. The total volume
to be injected is 11.1 gal/hr times 4 hr = 44.4 gal,
which is the same volume as calculated in the pre-
vious example. Note that because the fertilizer in-
jection time increased, the injection rate required to
apply the same 20 lb of N per acre decreased.

It is important to note that because citrus
microsprinkler irrigation systems do not irrigate
the entire soil surface, the fertilizers applied using
these systems will be placed only on the irrigated
portion of the soil surface. For example, if only 50
percent of the soil surface is irrigated with the
spray system in the above example, then the N ap-
plication rate in the irrigated zone will be 40 lb/
acre, and that in the non-irrigated zone will be 0 lb/
acre, to obtain the average rate of 20 lb/acre. Like-
wise, if only 20 percent of the soil surface is irri-
gated, the application rate in the irrigated area
would be 5 times the average on a gross acre basis.

Because water and fertilizers are not applied to
the entire soil surface when microirrigation sys-
tems are used, fertilizer applications to micro-irri-
gated crops are often made on the basis of indi-
vidual plants rather than on a gross acre basis. In
this case, Equation (2) applies:

Rate = [ 100 A Fp NP ] /[ P H W ] (2)
where F = amount of fertilizer to be applied per
plant (Ib/plant),
NP = number of plants per acre, and the other
terms are as previously defined.

For example, assume that 0.1 lb of N is to be ap-
plied to each tree in a 12-acre drip-irrigated grove


of young citrus trees. There are 200 trees per acre
(tree/ac). The drip irrigation system is operated for
3 hr per irrigation. After startup of the irrigation
system, fertilizer is injected for 2 hr, followed by
almost 1 hour of irrigation to flush the fertilizer
from the system. Then, for Ammonium Nitrate:

Rate = [100 12 ac 0.1 lb/tree 200 tree/ac]
[21% 2hr 10.73 lb/gal]
Rate = 53.3 gph

Thus, the required 0.1 lb of N per tree can be ap-
plied to 12 acres by injecting 53.3 gph for the 2 hr
of fertilizer injection time. The total volume to be
injected would be 53.3 gal/hr times 2 hr = 106.6 gal.

Center pivot irrigation systems
For center pivot irrigation systems, the required
fertilizer injection rate is calculated from:

Rate = [ 100 A F ] / [ P H W ] (3)
where H = fertilizer application time, normally the
time required to make 1 complete revolution of the
irrigation system, and all other terms are as previ-
ously defined.

Assume for example, that 30 lb of N will be ap-
plied per acre through a standard 160-acre (138
acres actually irrigated) center pivot irrigation sys-
tem. The fertilizer used is Urea-Ammonium Ni-
trate (28% N; 10.65 lb/gal). The irrigation time re-
quired to make 1 complete revolution is 48 hr. The
rate of injection can then be calculated as:

Rate = [ 100 138 ac 30 Ib/ac ]
[ 28% 48 hr 10.65 lb/gal ]
Rate = 28.9 gph

Thus, 28.9 gal of Urea-Ammonium Nitrate with
28 percent N must be injected per hour to apply 30
lbs of N per acre to the 138 acre area irrigated. A
total of 28.9 gal/hr times 48 hr = 1,388 gal must be
applied.

Traveling gun irrigation systems
For traveling gun irrigation systems, the injec-
tion rate is calculated from:

Rate = [ 100 S L F ] / [ 43,560 P W] (4)
where S = rate (speed) of traveler movement (ft/hr),
L = distance between travel lanes (ft), and all other
terms are as previously defined.








Assume for example, that 20 lb of N are to be
applied per acre to improved pasture irrigated with
a traveling gun system. Travel lane spacings are
200 ft and the traveler speed is 7 ft/min (420 ft/hr).
The fertilizer applied is Ammonium Nitrate (21%
N; 10.73 lb/gal). The required injection rate is cal-
culated from:

Rate = [100 420 ft/hr 200ft 20 lb/ac ]
[ 43,560 21% 10.73 lb/gal]
Rate = 17.1 gph

Thus the required 20 lb of N per acre would be
applied by injecting 17.1 gal of Ammonium Nitrate
per hour of traveling gun operation.

Safety
Make sure that the irrigation system compo-
nents will not be deteriorated by the fertilizer com-
pounds used. Handle fertilizers carefully. Wear
the appropriate protective clothing and protective
eyewear.

Florida law requires that irrigation systems into
which fertilizers are injected be equipped with
backflow prevention devices to protect the water


supply against contamination. Follow these regula-
tions by installing backflow prevention devices be-
fore beginning to inject fertilizers and by properly
maintaining and periodically testing your backflow
prevention system.

Summary
Fertigation is an appropriate production practice
for many Florida crops because of reduced nutrient
application costs and increased yields as compared
to conventional fertilizer application methods. Pro-
cedures for the calibration of fertilizer injection sys-
tems using chemical flow meters and volumetric
flow rate measurements were presented. Equa-
tions were given to calculate the required fertilizer
injection rates for solid set (sprinkler and micro),
center piv;t, and traveling gun irrigation systems.
Example problems were given for each of these
vpes of irrigation systems.

Fertilizers can be safely injected if proper safety
precautions are taken. Protect yourself by wearing
protective clothing and selecting and using injec-
tion equipment properly. Protect the water supply
by applying the right amount of fertilizers and by
using the proper backflow prevention equipment.


COOPERATIVE EXTENSION SERVICE, UNIVERSITY OF FLORIDA, INSTITUTE OF FOODANDAGRICULTURAL SCIENCES, John T. Woeste,
Director, in cooperation with the United States Department of Agriculture, publishes this information to further the purpose of the May 8 and June
30, 1914 Acts of Congress; and is authorized to provide research, educational information and other services only to individuals and institutions that
function without regard to race, color, sex, age, handicap or national origin. Single copies of extension publications (excluding 4-H and youth
publications) are available free to Florida residents from county extension offices. Information on bulk rates or copies for out-of-state purchasers
s availablefrom C.M. Hinton, Publications Distribution Center, IFAS Building 664, University of Florida, Gainesville, Florida32611. Before publicizing
this publication, editors should contact this address to determine availability. Printed 2/92.




Full Text

PAGE 1

was collected in 4 minutes, 31 seconds. To convert Calculating fertilizer injection ml to gal, divide by 3,785 ml/gal. Then 92 ml = 92/ 3,785 = 0.0243 gal. To convert seconds to hours, rates divide by 3,600 sec/hr. Then 4 min, 31 sec = 271 For all methods of injection, the required fertilsec, and 271/3,600 = 0.0753 hr. Finally, 0.0243 gal/ izer injection rate must be known. The required 0.0753 hr = 0.32 gal/hr. injection rate can be calculated from the following equations for solid set (including sprinkler and miFor many injection methods, the injection pump cro systems), center pivot and traveling gun irrigacalibration will change depending upon the prestion systems. sure in the irrigation system. The actual injection rate will be less when injecting against pressure. Solid set irrigation systems Therefore, the above procedure can be used only as Solid set systems include sprinkler and micro a first approximation of the final calibration set(drip and microsprinkler) irrigation systems. For ting, and the calibration will need to be finalized in solid set irrigation systems, the fertilizer injection the field during fertilizer injection into the irrigarate in gallons per hour (gph) is calculated from: tion system. Finalizing calibrations in the field Rate= [ 100 A F ] / [ P H W ] (1) where Rate = fertilizer injection rate (gph), To finalize the calibration of an injector, measure the rate of fertilizer depletion from the storage A = area to be ga (ac) tank. Install a small graduated supply tank if the F = fertilizer amount to be applied per acre (lb/ac), bulk storage tank is not graduated for accurate P = fertilizer fraction, percent of fertilizer per galmeasurement of volumes injected. lon of fluid injected (%), H = fertilizer application time (hr), and It is a good idea to inject fertilizers from a small fertilir oi graduated supply tank rather than to pump di-= of fertzer soluton rectly from a large bulk storage tank. The small tank should be sized to contain the fertilizer soluAs an example of the use of Equation (1), assume tion needed for one application, and only the that 20 lb of nitrogen (N) must be applied per acre required amount of fertilizer solution should be on a 5-acre citrus nursery using sprinkler irrigaplaced in the small tank before the irrigation durtion. The fertilizer to be used is a liquid solution of ing which it will be injected. This procedure can Ammonium Nitrate (21% N; 10.73 lb/gal)1.The improve the effectiveness of fertilizer injection benormal irrigation cycle is 2 hr, and fertilizer injeccause (1) only the amount of fertilizer in the small tion begins immediately after the system has supply tank can be injected during irrigation, thus reached normal operating pressure. Fertilizer will preventing excess applications from accidentally be injected for 1.5 hr, leaving almost 0.5 hr to flush being made, (2) the amount of fertilizer injected can the fertilizer from the irrigation system and off of easily and accurately be read if the supply tank is the plants. Using equation (1): relatively small and has graduations permanently marked on it, and (3) only the fertilizer in the small Rate = [100 * 5 ac * 20 lb/ac] tank will be diluted ifbackflow from the irrigation [21% * 1.5 hr * 10.73 lb/gall system occurs because of failure of the injection Rate = 29.6 gph pump and backflow prevention system. For injection methods which use a suction tubing Thus, the required 20 lb of N can be applied per between the injection pump and the supply tank, acre by injecting 29.6 gal of Ammonium Nitrate per the injection rate can be measured with a chemical hour for the 1.5 hr injection time. The total volume flow meter or by connecting the tubing to a graduto be injected would be 29.6 gal/hr times 1.5 hr = ated cylinder. Measurements should be made 44.4 gal. while the injector is operating under normal conditions, including normal injection rates and normal Si m i Because liquid fertilizer solutions are often custom mixed, the irrigation system operating pressures. Then adnutrient concentrations and weight of the fertilizer solution justments in the injection rate can be made as the must be obtained from the fertilizer supplier. Common values injection system operates. are used in this publication. 2



PAGE 1

If the above 20 lb of N per acre must be applied of young citrus trees. There are 200 trees per acre to a 5-acre citrus grove that is irrigated with a (tree/ac). The drip irrigation system is operated for microsprinkler system, Equation (1) can still be 3 hr per irrigation. After startup of the irrigation used. Assume that the micro system is operated for system, fertilizer is injected for 2 hr, followed by 6 hr at each irrigation and that fertilizer is injected almost 1 hour of irrigation to flush the fertilizer for 4 hr. Fertilizer injection begins immediately from the system. Then, for Ammonium Nitrate: after the system has reached normal operating pressure, leaving almost 2 hr to flush the fertilizer Rate = [100 * 12 ac * 0.1 lb/tree * 200 tree/ac] from the irrigation system. Then: [21% * 2hr * 10.73 lb/gal] Rate = [100 * 5 ac -20 lb/ac] Rate = 53.3 gph [21% * 4 hr * 10.73 Ib/gal] [21% 4 hr 10.73 lb/galhus, the required 0.1 lb of N per tree can be apRate = 11.1 gph plied to 12 acres by injecting 53.3 gph for the 2 hr of fertilizer injection time. The total volume to be Thus, the required 20 lb of N can be applied per injected would be 53.3 gal/hr times 2 hr = 106.6 gal. acre by injecting 11.1 gal of Ammonium Nitrate per hour for the 4 hr injection time. The total volume Center pivot irrigation systems to be injected is 11.1 gal/hr times 4 hr = 44.4 gal, For center pivot irrigation systems, the required which is the same volume as calculated in the prefertilizer injection rate is calculated from: vious example. Note that because the fertilizer injection time increased, the injection rate required to Rate = [ 100 * A F ] / [ P * H * W ] (3) apply the same 20 lb of N per acre decreased. where H = fertilizer application time, normally the time required to make 1 complete revolution of the It is important to note that because citrus time required to make complete revolution of the irrigation system, and all other terms are as previmicrosprinkler irrigation systems do not irrigate irrigation system, and all other terms are as previthe entire soil surface, the fertilizers applied using ously defined. these systems will be placed only on the irrigated portion of the soil surface. For example, if only 50 Assume for example, that 30 lb of N will be appercent of the soil surface is irrigated with the plied per acre through a standard 160-acre (138 spray system in the above example, then the N apacres actually irrigated) center pivot irrigation sysplication rate in the irrigated zone will be 40 lb/ tem. The fertilizer used is Urea-Ammonium Niacre, and that in the non-irrigated zone will be 0 lb/ trate (28% N; 10.65 lb/gal). The irrigation time reacre, to obtain the average rate of 20 lb/acre. Likequired to make 1 complete revolution is 48 hr. The wise, if only 20 percent of the soil surface is irrirate of injection can then be calculated as: gated, the application rate in the irrigated area would be 5 times the average on a gross acre basis. Rate = [ 100 * 138 ac * 30 lb/ac ] [ 28% * 48 hr * 10.65 lb/gal ] Because water and fertilizers are not applied to Rate = 28.9 gph the entire soil surface when microirrigation systems are used, fertilizer applications to micro-irriT 2 g gated crops are often made on the basis of indiThus, 28.9 gal of Urea-Ammonium Nitrate with vidual plants rather than on a gross acre basis. In 28 percent N must be injected per hour to apply 30 this case, Equation (2) applies: lbs of N per acre to the 138 acre area irrigated. A total of 28.9 gal/hr times 48 hr = 1,388 gal must be Rate = [ 100 A * Fp * NP ] /[ P -H * W ] (2) applied. where Fp = amount of fertilizer to be applied per Traveling gun irrigation systems plant (Ib/plant), p t , For traveling gun irrigation systems, the injecNP = number of plants per acre, and the other tion rate is calculated from: terms are as previously defined. Rate = [ 100 * S -L * F ] / [ 43,560 • P -W] (4) For example, assume that 0.1 lb of N is to be apwhere S = rate (speed) of traveler movement (ft/hr), plied to each tree in a 12-acre drip-irrigated grove L = distance between travel lanes (ft), and all other terms are as previously defined. 3



PAGE 1

"c. _ --_ January 1992 Circular 1033 S......N S T T U T E OF FOOD A N D A G R IC U L T U A LS.C EN ES Calibration of Fertilizer Injectors for Agricultural Irrigation Systems A. G. Smajstrla, D. Z. Haman and F. S. Zazueta* Florida Cooperative Extension Service / Institute of Food and Agricultural Sciences / University of Florida / John T. Woeste, Dean Fertilizer application through an irrigation sysCalibration of fertilizer injection ter is called "fertigation". Fertigation is practiced s em for several reasons -the primary reasons are sys lower application costs and greater production reEach method of fertilizer injection must be calisponses. It is normally less expensive to apply ferbrated by the user. Calibration procedures vary tilizers with irrigation water than by other methdepending upon the injection method used and ods, especially if several applications are required the specific design of the injection equipment. during the growing season. Also, for many Florida In all cases, however, the user must verify that the crops, growth and yields have been increased when manufacturer's calibration or the method being fertigation was used to maintain optimum nutrient used is correct by using a chemical flow meter levels at critical crop growth stages. which is accurate in the flow range of gallons per hour (or other rate being injected), or by measuring Other reasons for the popularity of fertigation the injection rate volumetrically. include: (1) the ability to make prescription applications of fertilizers; that is, to apply them precisely Chemical flow meters when needed and only in the amounts needed, thus Flow meters are available which can be used to maximizing their effectiveness, (2) a reduction in directly measure the chemical flow rate while the environmental pollution because fertilizers can be injection system is operating under field conditions. applied only in the amounts needed and thus large Meters can often be mounted on the low pressure quantities are not subject to leaching loss if heavy (suction) side of injection pumps. rainfalls follow conventional applications, and (3) a possible reduction in the total volume of fertilizers Caution: If a chemical flow meter is used on the applied because leaching losses are minimized, high pressure side of an injector, be certain that the flow meter is rated for the pressure being used beGrowers should only inject water soluble fertilizfore installing it in that position. Failure to use a ers or fertilizer suspensions that are compatible properly installed, adequately pressure-rated meter with their irrigation system and crop production may cause it to be damaged, and it may be hazardsystem. Because they are potentially corrosive, ous to individuals working in the area. fertilizers should be flushed from the irrigation system after each application. Fertilizer solutions Volumetric flow rate measurement should always be injected before (upstream of) the To measure flow rates volumetrically, a confilters in microirrigation systems. The compatibilof ow volume a a a clintainer of known volume (such as a graduated cylinity of fertilizer solutions with the irrigation water (sh as a at and with any other chemicals being injected should der) and an accurate timer (such as a stopwatch or a watch with second hand) are needed. Measure be tested to avoid the formation of chemical precipithe tied to the ner. e au ..the time required to fill the container. Then calcutates in the irrigation system. IFAS production s in te i o .WS p n late the flow rate as the volume per time, typically guides should be consulted for the specific crop belat t fls he oue r time, typic in units of gallons per hour (gal/hr or gph). ing produced to obtain recommendations for chemical formulations, fertigation rates and schedules. F e , For example, assume that a 100 ml graduated *Professor, and associate professors, Agricultural Engineering cylinder and stopwatch were used to measure injecDepartment, University of Florida, FL 32611. tion rates. Assume that 92 ml of fertilizer solution


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normalize
'109394' 'info:fdaE20090919_AAAALLfileF20090919_AACDPC' 'sip-files00001.pro'
6a1f6bdce417dbbd9cfebd3f4992a02d
85b5b59add31b0c92b63e029fdc6f33730edc8d8
'2012-04-03T14:49:39-04:00'
describe
'37442' 'info:fdaE20090919_AAAALLfileF20090919_AACDPD' 'sip-files00001.QC.jpg'
e8685df2f9f7d70d410e7fdeda15d545
794eea119c045fc8d6309a9addcc8ef4887b31dc
'2012-04-03T14:49:16-04:00'
describe
'1052680' 'info:fdaE20090919_AAAALLfileF20090919_AACDPE' 'sip-files00001.tif'
2cd7ca4a86cc22869cc5ef680a1cca79
046e74ba39a67825195e56c07c6285527e246981
'2012-04-03T14:49:18-04:00'
describe
'4356' 'info:fdaE20090919_AAAALLfileF20090919_AACDPF' 'sip-files00001.txt'
1bb9b4a29e54184bcc32a5a232f0c73c
4b73d4099875aa24dd8a80c1fc6519f8ed902e40
'2012-04-03T14:49:31-04:00'
describe
'9584' 'info:fdaE20090919_AAAALLfileF20090919_AACDPG' 'sip-files00001thm.jpg'
b7e1d4c4734d7d90099ccc3b89a5f8e0
1abd49f176203cea91db9d57987ebd9ef2598384
'2012-04-03T14:49:28-04:00'
describe
'217909' 'info:fdaE20090919_AAAALLfileF20090919_AACDPH' 'sip-files00002.jp2'
c3e2e55444968783028a188191c53ff7
56a38aeee0b92c4a5978ca45b85c58831d14f75d
'2012-04-03T14:49:12-04:00'
describe
'138012' 'info:fdaE20090919_AAAALLfileF20090919_AACDPI' 'sip-files00002.jpg'
f5c5e0c82bfcd2b9e89148c9419953cd
6fd3465c12552ce61650ddbcdc88005bf2cb7a0a
describe
'97101' 'info:fdaE20090919_AAAALLfileF20090919_AACDPJ' 'sip-files00002.pdf'
0a871b9858a5e60b4df09d86796a7ef4
37e8a8c80fc3af2386b189fc4797990437914934
'2012-04-03T14:49:32-04:00'
describe
'info:fdaE20090919_AAAALLfileF20090919_AACDPJ-norm-0' 'aip-filesF20090919_AACDPJ-norm-0.pdf'
f1f59ad7d39927e36766de20dc51726d
47d890447f3fa0f04054e853e39ccc8b1571d028
'2015-05-15T16:54:46-04:00'
describe
'2015-05-15T16:54:41-04:00'
normalize
'115657' 'info:fdaE20090919_AAAALLfileF20090919_AACDPK' 'sip-files00002.pro'
9442f316d5f17f6371f203f03264eaf3
35fa72a8c263c69f1f3745fcfdf74b4d6bcc6e51
describe
'36344' 'info:fdaE20090919_AAAALLfileF20090919_AACDPL' 'sip-files00002.QC.jpg'
44e3271adae3abcd63284aafbbbcfe6e
8f2a9a581d81c59454dd4fd0c8f81d2a9798887f
'2012-04-03T14:49:20-04:00'
describe
'1051496' 'info:fdaE20090919_AAAALLfileF20090919_AACDPM' 'sip-files00002.tif'
b8be89b0806969bddc4270ad124df20d
33665c1fb0af1ad1652b4e81a3364cf72559b53d
'2012-04-03T14:49:27-04:00'
describe
'4514' 'info:fdaE20090919_AAAALLfileF20090919_AACDPN' 'sip-files00002.txt'
f0b6ca5cbc112a454b6b7d985106d385
9ae320fdc433ec22df344fc6b3a5ebf7fac9d294
'2012-04-03T14:49:15-04:00'
describe
'8982' 'info:fdaE20090919_AAAALLfileF20090919_AACDPO' 'sip-files00002thm.jpg'
343cb39a8530511577698452dc765def
9a7f8ffa9a00f030505f86465f291a6866cb8d3a
'2012-04-03T14:49:13-04:00'
describe
'200845' 'info:fdaE20090919_AAAALLfileF20090919_AACDPP' 'sip-files00003.jp2'
ff17df4e756a82acf2882f3f752bb516
6c17e5a57ed61db57eac1476a536367a7777a479
'2012-04-03T14:49:34-04:00'
describe
'127688' 'info:fdaE20090919_AAAALLfileF20090919_AACDPQ' 'sip-files00003.jpg'
5bb4027dd65a1d15d7a799a6ff0f560b
cadbb7c1da5852568411ed87b2cf879caee201d2
'2012-04-03T14:49:36-04:00'
describe
'89676' 'info:fdaE20090919_AAAALLfileF20090919_AACDPR' 'sip-files00003.pdf'
a46fb32150980dfe63108351072c29d8
3c9235bdb81e0a4a36e07e8774f75b0326fbf913
describe
'info:fdaE20090919_AAAALLfileF20090919_AACDPR-norm-0' 'aip-filesF20090919_AACDPR-norm-0.pdf'
f1f59ad7d39927e36766de20dc51726d
47d890447f3fa0f04054e853e39ccc8b1571d028
'2015-05-15T16:54:45-04:00'
describe
'2015-05-15T16:54:34-04:00'
normalize
'108433' 'info:fdaE20090919_AAAALLfileF20090919_AACDPS' 'sip-files00003.pro'
699fc9d0911330d6381e924facf9c212
909687029ed45c8b430db67ef5213f0d22e89064
describe
'34287' 'info:fdaE20090919_AAAALLfileF20090919_AACDPT' 'sip-files00003.QC.jpg'
2a42588e86a876784fac957a8ac5020f
9efacd273df01a475c14c8e95bc59d36a60a09a0
'2012-04-03T14:49:19-04:00'
describe
'1054820' 'info:fdaE20090919_AAAALLfileF20090919_AACDPU' 'sip-files00003.tif'
72910c78081f7abad538084d76bb1b30
520a0bbd8f2fe1f15a3c8ddf1b8973ee715d888f
describe
'4284' 'info:fdaE20090919_AAAALLfileF20090919_AACDPV' 'sip-files00003.txt'
fc05082bbef222f32687bdef1b1f5be4
2274a69a8036e9590a2624a054e8e85d9405f8e7
'2012-04-03T14:49:14-04:00'
describe
WARNING CODE 'Daitss::Anomaly' Invalid character
'8800' 'info:fdaE20090919_AAAALLfileF20090919_AACDPW' 'sip-files00003thm.jpg'
ebc976be2e07b8e39e4ebf513c878d0f
ea996bc5b41f985534e72c638586f917b2be96a7
describe
'143147' 'info:fdaE20090919_AAAALLfileF20090919_AACDPX' 'sip-files00004.jp2'
1910d6fdef20eb6e4d89574e0da401d1
0ddb0b3f928819f38f753bfa83e433c0caaf829a
describe
'91159' 'info:fdaE20090919_AAAALLfileF20090919_AACDPY' 'sip-files00004.jpg'
b4498ce92b83d9d07b26b34f5c2013b6
eca59325d20a0c8cd17ae8c6e798d1d51ae2c7cd
'2012-04-03T14:49:29-04:00'
describe
'64029' 'info:fdaE20090919_AAAALLfileF20090919_AACDPZ' 'sip-files00004.pdf'
f5be6bd35d73005d6f6f05b43d651ecd
02ce0f81b74d2049506bd0a836c51969db03b510
'2012-04-03T14:49:17-04:00'
describe
'info:fdaE20090919_AAAALLfileF20090919_AACDPZ-norm-0' 'aip-filesF20090919_AACDPZ-norm-0.pdf'
f1f59ad7d39927e36766de20dc51726d
47d890447f3fa0f04054e853e39ccc8b1571d028
describe
'2015-05-15T16:54:37-04:00'
normalize
'81263' 'info:fdaE20090919_AAAALLfileF20090919_AACDQA' 'sip-files00004.pro'
6833ed6c8bc3734c7376d3be3e7c1f5d
722ebd9394908333d0b12ac09ff618c9f82cb46e
describe
'24686' 'info:fdaE20090919_AAAALLfileF20090919_AACDQB' 'sip-files00004.QC.jpg'
9f132f3aec9df125bbe268d1a3332629
b5d790e6e191552d1e94c84f97ad37bd183e8614
describe
'984436' 'info:fdaE20090919_AAAALLfileF20090919_AACDQC' 'sip-files00004.tif'
147cac0a52c090b7b8b81acbf22a5db0
d319fd6803c56bec9d4213f2d05d088ff6c30137
'2012-04-03T14:49:26-04:00'
describe
'3090' 'info:fdaE20090919_AAAALLfileF20090919_AACDQD' 'sip-files00004.txt'
829200d1ab4f72fe4f804d4233370fa8
d3bf6d81be1f8122f931f476035456fc3669c8cb
describe
'6573' 'info:fdaE20090919_AAAALLfileF20090919_AACDQE' 'sip-files00004thm.jpg'
3cb42bce889a39b5b572f7544b02ec08
d3c58d6afd091ce666c4376d0bfad0118624fc2a
describe
'15286' 'info:fdaE20090919_AAAALLfileF20090919_AACDQF' 'sip-filesUF00014464_00001.mets'
7a790ac9a219824802e9bbde9f6e2c4b
4699b5404a70f707888c299f1ad7ac9d66c35292
'2012-04-03T14:49:37-04:00'
describe
TargetNamespace.1: Expecting namespace 'http://www.uflib.ufl.edu/digital/metadata/ufdc2/', but the target namespace of the schema document is 'http://digital.uflib.ufl.edu/metadata/ufdc2/'.
'mixed'
xml resolution
http://www.uflib.ufl.edu/digital/metadata/ufdc2/ufdc2.xsd
BROKEN_LINK schema http://www.uflib.ufl.edu/digital/metadata/ufdc2/ufdc2.xsd
The element type "div" must be terminated by the matching end-tag "
".
TargetNamespace.1: Expecting namespace 'http://www.uflib.ufl.edu/digital/metadata/ufdc2/', but the target namespace of the schema document is 'http://digital.uflib.ufl.edu/metadata/ufdc2/'.
'17246' 'info:fdaE20090919_AAAALLfileF20090919_AACDQI' 'sip-filesUF00014464_00001.xml'
bca66e828f94df9543149b92d5ad9e3c
0504739a67353463147cb33b3126320986760956
describe
TargetNamespace.1: Expecting namespace 'http://www.uflib.ufl.edu/digital/metadata/ufdc2/', but the target namespace of the schema document is 'http://digital.uflib.ufl.edu/metadata/ufdc2/'.
xml resolution
http://www.uflib.ufl.edu/digital/metadata/ufdc2/ufdc2.xsd
http://www.uflib.ufl.edu/digital/metadata/ufdc2/ufdc2.xsd
The element type "div" must be terminated by the matching end-tag "".
TargetNamespace.1: Expecting namespace 'http://www.uflib.ufl.edu/digital/metadata/ufdc2/', but the target namespace of the schema document is 'http://digital.uflib.ufl.edu/metadata/ufdc2/'.



PAGE 1

Assume for example, that 20 lb of N are to be supply against contamination. Follow these regulaapplied per acre to improved pasture irrigated with tions by installing backflow prevention devices bea traveling gun system. Travel lane spacings are fore beginning to inject fertilizers and by properly 200 ft and the traveler speed is 7 ft/min (420 ft/hr). maintaining and periodically testing your backflow The fertilizer applied is Ammonium Nitrate (21% prevention system. N; 10.73 lb/gal). The required injection rate is calculated from: Summary Fertigation is an appropriate production practice Rate = [100 * 420 ft/hr * 200ft * 20 lb/ac ] for many Florida crops because of reduced nutrient [ 43,560 * 21% * 10.73 lb/gal] application costs and increased yields as compared Rate = 17.1 gph to conventional fertilizer application methods. ProRate = 17.1 gph cedures for the calibration of fertilizer injection systems using chemical flow meters and volumetric Thus the required 20 lb of N per acre would be flow rate measurements were presented. Equaapplied by injecting 17.1 gal of Ammonium Nitrate tions were given to calculate the required fertilizer per hour of traveling gun operation, injection rates for solid set (sprinkler and micro), Safety center pit, and traveling gun irrigation systems. Example problems were given for each of these Make sure that the irrigation system compovpes of irrigation systems. nents will not be deteriorated by the fertilizer compounds used. Handle fertilizers carefully. Wear Fertilizers can be safely injected if proper safety the appropriate protective clothing and protective precautions are taken. Protect yourself by wearing eyewear. protective clothing and selecting and using injection equipment properly. Protect the water supply Florida law requires that irrigation systems into by applying the right amount of fertilizers and by which fertilizers are injected be equipped with using the proper backflow prevention equipment. backflow prevention devices to protect the water COOPERATIVE EXTENSION SERVICE, UNIVERSITY OF FLORIDA, INSTITUTE OF FOODANDAGRICULTURAL SCIENCES, John T. Woeste, Director, in cooperation with the United States Department of Agriculture, publishes this information to further the purpose of the May 8 and June 30, 1914 Acts of Congress; and is authorized to provide research, educational information and other services only to individuals and institutions that function without regard to race, color, sex, age, handicap or national origin. Single copies of extension publications (excluding 4-H and youth publications) are available free to Florida residents from county extension offices. Information on bulk rates or copies for out-of-state purchasers s availablefrom C.M. Hinton, Publications Distribution Center, IFAS Building 664, University of Florida, Gainesville, Florida32611. Before publicizing this publication, editors should contact this address to determine availability. Printed 2/92.