1. Bucket Chemistry 101 Bodie Pennisi, Paul Thomas and Mel Garber
Extension Horticulture Specialists
The University of Georgia

2. Bucket Chemistry

4. Fertilizer Problems Are Not That Bad !

5. The Way To Tackle Them Is …

6. Greenhouse Crops and Fertilizer Recommendations

7. Fertilizer Stock Tank
This is a photo of the fertilizer stock tank. Concentrated solution is pumped out of it, injected into the water line, and distributed to the plants.

8. PROPORTIONER
A device used in a fertigation system to control the rate of fertilizer applied through the system.
This is a proportioner used in a fertigation system to control the rate of fertilizer applied through the system. It is the blue device attached to the green stock tank. The stock tank can vary in size from a 5 gallon bucket to a 2,000 gallon tank.

9. 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

10. 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
1:50 =
1:100 = 1:200 = 1:500 = 2%
1% 0.5% 1%
To get from ratios to percent:
(1/50) x 100 = 2%
To get from percent to ratios :
100/2%=1:50

11. Parts per million (ppm)
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

12. 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:
Injection ratio
Example: 1:100
Size of stock tank in gallons
Example: 25 gallons

13. Weight Basis
Example: A chrysanthemum grower gets a recommendation to apply 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 1:30 injection ratio will be used?

14. Things You Need To Know To Solve This Problem:
Recommended fertilizer application rate.
16 ounces per 100 gal
2. Fertilizer formulation and analysis.
Injection ratio
1:30
Size of stock tank in gallons
25 gallons

15. 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 = oz of
100 / 25 gal

16. 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 = oz per 25 1:30 ratio

17. Commercial Fertilizer (ppm)
Example: A pansy grower gets a recommendation to apply 150 ppm nitrogen using water-soluble formulation.
How much fertilizer should be mixed in a 25 gallon stock tank if an injector with a 1:100 injection ratio will be used?

18. Things You Need To Know To Solve This Problem:
Recommended fertilizer application rate.
150 ppm nitrogen
2. Fertilizer formulation and analysis.
Injection ratio
1:100
Size of stock tank in gallons
25 gallons

19. 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 gal equals 75 ppm
1 oz = 28 g or 28,000 mg
28,000 mg ÷ 379 L = ppm
( 1 gal = 3.79 L 100 gal = 379 L )

20. 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 = oz of per 100 gal
20 % x (final solution)

21. 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 = oz of per 25 gal
100 / 25 gal

22. Solution
Step 3: Use equation 2 to adjust the rate for a 1:100 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 1:100 injection ratio

23. 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
16 oz /lb ( in a 25 gallon stock tank)
This will give you 150 ppm with a 1/100 ratio
Are You Done ?

24. Not Yet !
How many parts per million of actual phosphorus and potassium will be applied with the 150 ppm N from the ?
Equation 4:
Oz fertilizer per 100 gal x 0.75 x percent nutrient =
the ppm desired nutrient .
Phosphorus 10.0 oz per 100 gal x x 10% P2O5
= 75 ppm P2O5

25. Not Yet ! For actual phosphorus :
P2O5 is actually only 44% elemental phosphorus
Therefor
75 ppm P2O5 x = 33 ppm actual phosphorus

26. Equation 4 – Now lets find the potassium true value!
Oz fertilizer per 100 gal x 0.75 x percent nutrient
= ppm desired nutrient
Potassium oz per 100 gal x x 20% K2O
= 150 ppm K2O in solution
For actual potassium : K2O is 83% elemental potassium
150 ppm K2O x = ppm actual potassium

27. Final analysis: 150 ppm N : 33 ppm P : 124.5 ppm K