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

Bucket Chemistry

Fertilizer Problems Are Not That Bad !

The Way To Tackle Them Is …

Greenhouse Crops and Fertilizer Recommendations

Fertilizer Stock Tank

PROPORTIONER PROPORTIONER A device used in a fertigation system to control the rate of fertilizer applied through the system.

Stock Fertilizer Tank Injector ratio 1 : 100 Fertilizer Injector or Proportioner Water line Irrigation line to plants 1 part stock solution 100 parts of water

Stock Tank 1:50 = 1:50 = 1:100 = 1:200 = 1:500 = Water line 1 part stock solution x parts of water 5 gal etc. Fertilizer Injector or Proportioner 2% 1% 0.5% 1% Injector ratios To get from ratios to percent: (1/50) x 100 = 2% To get from percent to ratios : 100/2%=1:50

Parts per million (ppm) One part of a substance into one million parts of another substance 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

Things You Need To Know To Solve ppm Problems: 1.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 4.Size of stock tank in gallons Example: 25 gallons

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?

Things You Need To Know To Solve This Problem: 1.Recommended fertilizer application rate. 16 ounces per 100 gal 2. Fertilizer formulation and analysis Injection ratio 1:30 4.Size of stock tank in gallons 25 gallons

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 / 25 gal

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

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? How much fertilizer should be mixed in a 25 gallon stock tank if an injector with a 1:100 injection ratio will be used?

Things You Need To Know To Solve This Problem: 1.Recommended fertilizer application rate. 150 ppm nitrogen 2. Fertilizer formulation and analysis Injection ratio 1:100 4.Size of stock tank in gallons 25 gallons

1 oz / 100 gal = 75 ppm The Rule of 75 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 = ppm ( 1 gal = 3.79 L100 gal = 379 L )

Solution Step 1: Convert the ppm recommendation to a weight basis using the following equation: Equation 3 desired ppm = oz fertilizer per 100 gal desired ppm = oz fertilizer per 100 gal % of fertilizer nutrient x ppm = 10.0 oz of per 100 gal 20 % x 0.75(final solution)

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 per 25 gal 100 / 25 gal

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 = oz per 25 gal using a 1:100 injection ratio oz per 25 gal using a 1:100 injection ratio

Solution Step 4: Convert ounces to pounds and ounces where: 16 ounces = 1 pound (dry) oz per 25 gal = 15 lbs 10 oz oz/lb (....in a 25 gallon stock tank) 16 oz /lb (....in a 25 gallon stock tank) This will give you 150 ppm with a 1/100 ratio Are You Done ?

Equation 4: Oz fertilizer per 100 gal x 0.75 x percent nutrient = Oz fertilizer per 100 gal x 0.75 x percent nutrient = the ppm desired nutrient. the ppm desired nutrient. Not Yet ! How many parts per million of actual phosphorus and potassium will be applied with the 150 ppm N from the ? Phosphorus10.0 oz per 100 gal x 0.75 x 10% P 2 O 5 = 75 ppm P 2 O 5

Not Yet ! For actual phosphorus : P 2 O 5 is actually only 44% elemental phosphorus Therefor 75 ppm P 2 O 5 x 0.44 = 33 ppm actual phosphorus

Equation 4 – Now lets find the potassium true value! Oz fertilizer per 100 gal x 0.75 x percent nutrient = ppm desired nutrient = ppm desired nutrient Potassium 10.0 oz per 100 gal x 0.75 x 20% K 2 O = 150 ppm K 2 O in solution = 150 ppm K 2 O in solution For actual potassium : K 2 O is 83% elemental potassium For actual potassium : K 2 O is 83% elemental potassium 150 ppm K 2 O x 0.83 = ppm actual potassium

Final analysis: 150 ppm N : 33 ppm P : ppm K