Bucket Chemistry 101

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Bucket Chemistry 101

• Bodie Pennisi, Paul Thomas and Mel Garber
• Extension Horticulture Specialists
• The University of Georgia

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Bucket Chemistry
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(No Transcript)
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Fertilizer Problems Are Not That Bad !
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The Way To Tackle Them Is
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Greenhouse Crops and Fertilizer
Recommendations
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Fertilizer Stock Tank
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PROPORTIONER A device used in a fertigation
system to control the rate of fertilizer applied
through the system.
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Fertilizer Injector or Proportioner
Stock Fertilizer Tank
1 part stock solution
Water line
100 parts of water
Injector ratio 1 100
Irrigation line to plants
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Fertilizer Injector or Proportioner
Stock Tank
Water line
1 part stock solution
5 gal 25 50 100 200 500 etc.
x parts of water
Injector ratios
2 1 0.5 1
150 1100 1200 1500
To get from ratios to percent (1/50) x 100 2
To get from percent to ratios 100/2150
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Fertilizer recommendations for greenhouse crops
are given as either ppm of a specific fertilizer
nutrient or in pounds and ounces (weight basis)
of a fertilizer formulation per 100 gallons of
water
Parts per million (ppm) One part of a
substance into one million parts of another
substance
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Things You Need To Know To Solve ppm
Problems

• Recommended fertilizer application rate.
• Example 8 ounces per 100 gal or 200 ppm
  nitrogen
• 2. Fertilizer formulation and analysis.
• Example 20-10-20
• Injection ratio
• Example 1100
• Size of stock tank in gallons
• Example 25 gallons

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Weight Basis
Example A chrysanthemum grower gets a
recommendation to apply 20-20-20 water-soluble
formulation to a final concentration of 16 oz per
100 gallons of water. How much fertilizer
should be mixed in a 25 gallon stock tank if an
injector with a 130 injection ratio will be used?
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Things You Need To Know To Solve This
Problem

• Recommended fertilizer application rate.
• 16 ounces per 100 gal
• 2. Fertilizer formulation and analysis.
• 20-20-20
• Injection ratio
• 130
• Size of stock tank in gallons
• 25 gallons

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Solution
Step 1 Adjust the rate for the stock tank
size using the following equation Equation
1 oz per 100 gal oz fertilizer per stock
tank 100 / Stock Tank Size (gal)
16.0 oz per 100 gal 4.0 oz of
20-20-20 100 / 25 gal
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Solution
Step 2 Adjust the rate for the injection
ratio Equation 2 oz per stock tank x injector
ratio oz per stock tank using injector
4.0 oz per 25 gal x 30 120.0 oz per 25 gal _at_
130 ratio
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Commercial Fertilizer (ppm)
Example A pansy grower gets a recommendation to
apply 150 ppm nitrogen using 20-10-20
water-soluble formulation. How much fertilizer
should be mixed in a 25 gallon stock tank if an
injector with a 1100 injection ratio will be
used?
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Things You Need To Know To Solve This
Problem

• Recommended fertilizer application rate.
• 150 ppm nitrogen
• 2. Fertilizer formulation and analysis.
• 20-10-20
• Injection ratio
• 1100
• Size of stock tank in gallons
• 25 gallons

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The Rule of 75
1 oz / 100 gal 75 ppm
HOW DID WE GET THIS ?
One ounce (28 grams) of any pure dry
substance that will dissolve 100 in a
volume of 100 gal equals 75 ppm
1 oz 28 g or 28,000 mg 28,000 mg 379 L
73.88 ppm ( 1 gal 3.79 L 100 gal 379 L )
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Solution
Step 1 Convert the ppm recommendation to a
weight basis using the following
equation Equation 3 desired ppm
oz fertilizer per 100 gal of
fertilizer nutrient x 0.75
150 ppm 10.0 oz of 20-10-20 per 100 gal 20
x 0.75 (final solution)
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Solution
Step 2 Use equation 1 to adjust for a stock
tank size of 25 gallons oz per 100 gal
oz fertilizer per tank 100 / Tank Size (gal)
10.0 oz per 100 gal 2.5 oz of 20-10-20 per
25 gal 100 / 25 gal
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Solution
Step 3 Use equation 2 to adjust the rate for a
1100 injection ratio (In other words,
concentrate it! ) oz per stock tank x injector
ratio oz per stock tank using
injector
2.5 oz per 25 gal x 100 250.0 oz per 25 gal
using a 1100 injection ratio
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Are You Done ?
Solution
Step 4 Convert ounces to pounds and ounces
where 16 ounces 1 pound (dry) 250.0 oz
per 25 gal 15 lbs 10 oz 20-10-20
16 oz /lb (. . . .in a 25 gallon
stock tank) This will give you 150 ppm with a
1/100 ratio
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Not Yet !
How many parts per million of actual phosphorus
and potassium will be applied with the 150 ppm N
from the 20-10-20 ?
Equation 4 Oz fertilizer per 100 gal x 0.75
x percent nutrient the ppm desired nutrient
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Phosphorus 10.0 oz per 100 gal x 0.75 x 10
P2O5 75 ppm P2O5
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Not Yet !
For actual phosphorus P2O5 is actually only
44 elemental phosphorus Therefor 75 ppm P2O5 x
0.44 33 ppm actual phosphorus
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Equation 4 Now lets find the potassium true
value! Oz fertilizer per 100 gal x 0.75 x
percent nutrient ppm desired
nutrient Potassium 10.0 oz per 100 gal x
0.75 x 20 K2O 150 ppm K2O in
solution For actual potassium K2O is 83
elemental potassium 150 ppm K2O x 0.83
124.5 ppm actual potassium
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Final analysis 150 ppm N 33 ppm P
124.5 ppm K