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January 1986
G14
Disk(s) under separate cover
Circular 694
A Microcomputer Program for
Dilution Calculations
When Injecting Solution Fertilizers
COMPUTER SERIES Central Science
Central Science
Library
Thomas H. Yeager and Dewayne L. Ingram
U JAN 30 1990
University of Florida
mmi
101
F6 3 6c itive Extension Service / Institute of Food and Agricultural Sciences / University of Florida / John T. Woeste, Dean
/ 694
A Microcomputer Program for
Dilution Calculations When Injecting
Solution Fertilizers
Thomas H. Yeager and Dewayne L. Ingram
Extension Ornamental Horticulturists
Ornamental Horticulture Department
IFAS, University of Florida
Copyright, 1985, IFAS, UF
The authors gratefully acknowledge Jason Goldman, Ivan Milman and
Justine Wetherington for assistance in writing SOLUFERT in BASIC
computer language.
UNIVi.RSITY OF FLORIDA LIBRARIES
INTRODUCTION
Computations that are lengthy, cumbersome, and require several
conversion factors are often required for injecting fertilizer in
irrigation water. Consequently, many nursery operators are
reluctant to use fertilizers applied by irrigation water. The
computer program described below has been developed to perform
these computations quickly. SOLUFERT, Dilution Calculations When
Injecting Solution Fertilizers, is an interactive computer program
(requires user input) that will calculate the dilution ratio needed
to obtain the desired concentration of nitrogen, phosphorus, or
potassium in the irrigation water. Refer to microcomputer program
"Dilution Calculations When Injecting Dissolved Dry Fertilizers"
(Circular 693) for fertilizers that are purchased dry and dissolved
before being injected into irrigation water. SOLUFERT, as outlined
in Figure 1, is written in BASIC.
CONFIGURATIVE REQUIREMENTS
1. IBM or compatible microcomputer
2. MS-DOS Operating System
3. 64 K Memory
4. Monochrome or color display
5. Single Disk Drive
6. Printer (optional)
HOW TO BEGIN
1. Turn your computer on. Use your regular boot (DOS) disk.
2. Place SOLUFERT disk into the drive unit.
3. Type SOLUFERT (press the return key).
If you wish to view the credits and a brief description of
this program, simply type in the letter C and press . If
you want to start the program, just press the key.
After the credits and abstract have been viewed or skipped,
the following must be obtained:
1. Analysis or grade (example, 8-8-8) of fertilizer. This is the
percent of nitrogen (N), phosphorus pentoxide (P205), and
potassium oxide (K20) in the fertilizer.
2. Parts per million (ppm) nitrogen (N), phosphorus (P), or
potassium (K) desired in the irrigation water. The irrigation
water may contain naturally occurring nitrogen, phosphorus, or
potassium for which the concentration can be determined by
chemical analysis.
3. Weight/volume ratio for the fertilizer. Solution fertilizers
are commonly sold by the ton and gallons of liquid per ton
varies with the product and temperature. The manufacturer
should be able to provide the weight/volume ratio.
4. Dilution ratio(s) of the injector. A dilution ratio indicates
how much the injector or proportioner will dilute the
fertilizer concentrate. For example, a dilution ratio of 1:
1000 will result in 999 gallons of water being mixed with one
gallon of fertilizer concentrate. Some injectors have variable
dilution ratios.
Utilizing the inputs outlined above for your situation, this
computer program will calculate the dilution ratio needed to
achieve the desired concentration of nitrogen, phosphorus, or
potassium. If the dilution ratio does not equal the one you
selected, the program will indicate how to dilute the concentrated
fertilizer before injection or will give the analysis of solution
fertilizer needed to achieve the desired concentration of nitrogen,
phosphorus, or potassium, to be applied by irrigation water.
SAMPLE RUN
The following inputs as outlined above will be used for the
sample run.
1. 10-5-15
2. N
3. 150
4. 10
5. B
6. 11.69
7. 1000
Letters or numbers in quotes are entered by the user. Quotes
are not entered. Phrases in boxes are viewed on the screen.
The first number is percent nitrogen (N), the second, percent
phosphorus pentoxide (P205), and the third potassium oxide (K20).
2. What element do you want to base the calculations
on?
Enter N for Nitrogen
P for Phosphorus
K for Potassium.
"N"
3. What concentration in parts per million (ppm) of
NITROGEN do you desire?
"150" ppm NITROGEN
Nitrogen was selected in question 2 as the element on which to base
the calculations, so question 3 asks for the nitrogen
concentration. If phosphorus or potassium had been entered in
question 2, question 3 would have asked for the concentration of
phosphorus or potassium, respectively.
If phosphorus or potassium had been chosen in question 2, the
1. What is your fertilizer analysis? (Press return
after each number.)
1"
10 "5"
10 5 "15"
10 5 "15"
concentration entered in question 3 (the desired concentration) is
the elemental concentration of phosphorus and potassium and not the
concentration of the oxides (P205 and K20, respectively).
note: ppm P205 x .436 = ppm elemental phosphorus
ppm K20 x .83 = ppm elemental potassium
4. What ppm nitrogen, phosphorus, and potassium are
naturally in the irrigation water?
Enter the number 0 if not known.
"10" ppm NITROGEN
"0" ppm PHOSPHORUS
"0" ppm POTASSIUM
Values entered for question 4 must be elemental concentrations and
not oxides. If the concentration of nitrogen, phosphorus, or
potassium naturally in the irrigation water is not known, enter 0,
but naturally occurring nitrogen, phosphorus, or potassium will
increase the concentration applied above that desired in question
3. For this example, it has been determined by chemical analysis
that the irrigation water contains 10 ppm nitrogen. The irrigation
water did not contain natural phosphorus or potassium.
Natural concentrations of nitrogen, phosphorus, and potassium
in the irrigation water may vary frequently, so it is important to
monitor frequently their concentration in order to apply precise
concentrations. It is possible that the irrigation water contains
a higher concentration of nitrogen, phosphorus, or potassium than
you want
required
to inject. Consequently, that elements) would not be
in the fertilizer.
5. You must either provide the weight/volume ratio of
the concentrated fertilizer or choose to accept a
default of 10 pounds/gallon (200 gallons/ton).
Enter A for gallons/ton
B for pounds/gallon
C for the default.
"B"
The fertilizer distributor says the 10-5-15 weighs 11.69 pounds per
gallon of fertilizer, so "B" is entered to select the appropriate
units for computation. Selection of the default can result in
erroneous answers.
6. What is the weight/volume ratio? (enter the number
10 to default)
"11.69" pounds/gallon
The numerical weight obtained from the fertilizer distributor
is entered. The units following the number were selected in
question 5.
The computer uses the above inputs and calculates the injector
setting needed to achieve desired concentration of fertilizer
element in the irrigation water. The following message is
displayed.
7. An injector setting of 1: 1000 is required to
supply 150 ppm NITROGEN in the irrigation water
using the 10-5-15 fertilizer. Please enter the
closest setting that you can supply such that the
setting is less than or equal to the setting
needed. If this is not possible, then input the
next higher setting.
Your setting 1: "1000"
The setting or injector dilution ratio entered is equal to injector
dilution ratio calculated by the computer. Thus, the irrigation
water applied to plants contains 150 ppm nitrogen or the desired
concentration.
Nitrogen, phosphorus, and potassium concentrations in the
irrigation water are displayed as follows:
When using an injector setting of 1:1000 and the
10-5-15 fertilizer, water applied to plants
contains:
150 ppm NITROGEN
30.5 ppm PHOSPHORUS
174.3 ppm POTASSIUM.
The 10-5-15 fertilizer contains three elements.
Suppose you had entered a number for your injector setting
that is less than the dilution needed to obtain 150 ppm nitrogen.
Note the following example:
Your setting 1: "100"
The irrigation water would contain 1410.7 ppm
NITROGEN when using the 1:100 dilution ratio and
the 10-5-15 fertilizer. Do you wish to use a
mixing tank to obtain 150 ppm NITROGEN in the
irrigation water? Enter Y for yes or N for no.
"N"
When using an injector setting of 1:100 and the
10-5-15 fertilizer, water applied to plants
contains:
1410.7 ppm NITROGEN
305.3 ppm PHOSPHORUS
1743.9 ppm POTASSIUM.
A mixing tank is used to dilute and mix the concentrated fertilizer
prior to injection. Suppose you entered "Y" instead of "N" for the
last entry.
What will be the total number of gallons (water
and fertilizer) in your mixing tank?
"50" gallons
To make a 50 gallon solution of water and
fertilizer, take 4.9 gallons of the 10-5-15
fertilizer and add irrigation water up to 50
gallons. The 50 gallon solution in the mixing
tank is injected into the irrigation water using a
1: 100 dilution ratio.
Water applied to plants contains:
150 ppm NITROGEN
30.5 ppm PHOSPHORUS
174.3 ppm POTASSIUM.
Suppose you had entered a number for the injector setting that is
larger than the dilution needed to obtain 150 ppm nitrogen.
Note the following example:
Your setting 1: "2000"
The following message would be viewed.
Using the 1:2000 dilution and the 10-5-15 fertilizer,
the maximum NITROGEN concentration in the irrigation
water will be 80 ppm. If 150 ppm NITROGEN are desired,
a 19.9 percent NITROGEN fertilizer must be used.
If the calculations were based on phosphorus or potassium, the
percentage needed in the fertilizer would be given as the oxides,
P205 and K20, respectively.
When an answer is displayed, other pertinent information for
the injection process is also viewed on the screen. The function
"print screen" may be used for a hard copy of the information
needed for the fertilizer injection process.
You may elect to repeat or end the program.
COMPUTATIONAL FORMULAS
The following formula is used to calculate the parts per
million of an element (ppmexp) in irrigation water for a specific
injector setting.
ppmexp = nat + ((wt*rat*1198.26)/yrset)
nat = naturally occurring ppm of element in irrigation water
wt = percentage of element in fertilizer
The percentage of phosphorus pentoxide and potassium oxide in
the fertilizer is multiplied by 0.436.and 0.83, respectively,
to obtain the percentage of phosphorus (wt) and potassium (wt)
in the fertilizer. /
rat = weight/volume (lb/gal) ratio of the solution
fertilizer
1198.26 mg-gal/lb-liter = 453.59 g/lb *1000 mg/g 1 gal/3.78
liter 1/100
yrset = your injector dilution
If the injector setting used is smaller than needed to obtain
the desired ppm of element, the solution fertilizer can be dil'-ted
before injection. The following formula is used to calculate the
dilution factor (dfact).
dfact = (ppmx/yrset)/(ppm-nat)
ppmx = wt rat 1198.26
ppm = ppm desired
The gallons of fertilizer (gfert) diluted to a specified volume
(mixer) prior to injection are then calculated.
gfert = mixer/dfact
If the injector setting used is larger than needed to obtain
the desired ppm, fertilizer with a higher analysis of the desired
element must be selected. The percentage 1) nitrogen concept) 2)
phosphorus pentoxide, or 3) potassium oxide of the fertilizer
analysis is obtained using the following formula.
concept = (ppm nat) yrset/(rat 1198.26)
1 concept = %N
2 concep/0.436 = %P205
3 concep/0.83 = %K20
A flow chart for the fertilizer dilution program is provided
on the following page.
Figure 1. Fertilizer dilution program flow chart.
YES
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