Bucket Bucket Chemistry 101Chemistry 101Bodie Pennisi, and Paul ThomasBodie Pennisi, and Paul Thomas

Extension Horticulture Extension Horticulture Specialists Specialists

The University of GeorgiaThe University of Georgia

Bucket ChemistryBucket Chemistry

Fertilizer Fertilizer Problems Are Problems Are Not That Bad !Not That Bad !

The Way To The Way To Tackle Them Is Tackle Them Is

……

Greenhouse Greenhouse Crops and Crops and Fertilizer Fertilizer

RecommendatioRecommendations ns

Fertilizer Fertilizer Stock TankStock Tank

PROPORTIONERPROPORTIONERA device used A device used in a fertigation in a fertigation

system to system to control the control the

rate of rate of fertilizer fertilizer applied applied

through the through the system.system.

Stock Stock FertilizeFertilizer Tankr Tank

Injector Injector ratio ratio

1 : 1001 : 100

Fertilizer Injector or Fertilizer Injector or ProportionerProportioner

Water Water lineline

Irrigation Irrigation line to line to plantsplants

1 1 part part stock stock solutisoluti

onon100 100

parts parts of of

waterwater

Stock Stock TankTank

1:50 1:50 = =

1:100 1:100 = 1:200 = 1:200 = 1:500 = 1:500

= =

Water Water lineline1 part 1 part

stock stock solutisoluti

ononx parts of x parts of

waterwater5 gal5 gal25255050100100200200500 500 etc.etc.

Fertilizer Injector or Fertilizer Injector or ProportionerProportioner

2% 2% 1% 1% 0.5% 0.5% 0.1%0.1%

Injector Injector ratiosratios

To get from ratios to percent:To get from ratios to percent:(1/50) x 100 = 2%(1/50) x 100 = 2%

To get from percent to ratios :To get from percent to ratios :100/2%=1:50100/2%=1:50

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

another substanceanother substance

Fertilizer recommendations for Fertilizer recommendations for greenhouse crops are given as greenhouse crops are given as

either ppm of a specific either ppm of a specific fertilizer nutrient or in pounds fertilizer nutrient or in pounds and ounces (weight basis) of a and ounces (weight basis) of a fertilizer formulation per 100 fertilizer formulation per 100

gallons of watergallons of water

Things You Need To Things You Need To Know To Solve ppm Know To Solve ppm

Problems:Problems:1.1. Recommended fertilizer application Recommended fertilizer application

rate.rate.Example: 8 ounces per 100 gal or Example: 8 ounces per 100 gal or 200 ppm nitrogen200 ppm nitrogen

2. Fertilizer formulation and analysis.2. Fertilizer formulation and analysis.Example: 20-10-20Example: 20-10-20

3.3. Injection ratioInjection ratioExample: 1:100Example: 1:100

4.4. Size of stock tank in gallonsSize of stock tank in gallonsExample: 25 gallonsExample: 25 gallons

Weight BasisWeight BasisExample: A chrysanthemum grower Example: A chrysanthemum grower

gets a recommendation to apply gets a recommendation to apply 20-20-20-2020-20 water-soluble formulation to a water-soluble formulation to a final concentration of final concentration of 16 oz per 100 16 oz per 100 gallonsgallons of water. of water.

How much fertilizer should be mixed How much fertilizer should be mixed in a in a 25 gallon stock tank25 gallon stock tank if an if an injector with a injector with a 1:30 injection ratio1:30 injection ratio will be used?will be used?

Things You Need To Things You Need To Know To Solve This Know To Solve This

Problem:Problem:1.1.Recommended fertilizer Recommended fertilizer application rate.application rate.16 ounces per 100 gal16 ounces per 100 gal

2. Fertilizer formulation and 2. Fertilizer formulation and analysis.analysis.20-20-2020-20-20

3.3.Injection ratioInjection ratio1:301:30

4.4.Size of stock tank in gallonsSize of stock tank in gallons25 gallons25 gallons

SolutionSolutionStep 1: Adjust the rate for the stock Step 1: Adjust the rate for the stock

tank size using the following tank size using the following equation:equation:

Equation 1Equation 1oz per 100 galoz per 100 gal = oz fertilizer = oz fertilizer per stock tankper stock tank

100 / Stock Tank Size (gal)100 / Stock Tank Size (gal)16.0 oz per 100 gal16.0 oz per 100 gal = = 4.0 oz of 20-4.0 oz of 20-20-2020-20100 / 25 gal100 / 25 gal

SolutionSolution

Step 2: Adjust the rate for the Step 2: Adjust the rate for the injection ratio:injection ratio:

Equation 2Equation 2

oz per gallon x injector ratio = oz per gallon x injector ratio = oz per stock tank oz per stock tank

4.0 oz per 25 gal x 30 = 4.0 oz per 25 gal x 30 = 120.0 oz 120.0 oz per 25 gal tank!per 25 gal tank!

Commercial Fertilizer Commercial Fertilizer (ppm)(ppm)

Example: A pansy grower Example: A pansy grower gets a recommendation to gets a recommendation to apply 150 ppm nitrogen apply 150 ppm nitrogen using using 20-10-2020-10-20 water- water-soluble formulation.soluble formulation.

How much fertilizer should How much fertilizer should be mixed in a be mixed in a 25 gallon 25 gallon stock tankstock tank if an injector if an injector with a with a 1:100 injection ratio1:100 injection ratio will be used?will be used?

Things You Need To Things You Need To Know To Solve This Know To Solve This

Problem:Problem:1.1. Recommended fertilizer application Recommended fertilizer application rate.rate.150 ppm nitrogen150 ppm nitrogen

2. Fertilizer formulation and analysis.2. Fertilizer formulation and analysis.20-10-2020-10-20

3.3. Injection ratioInjection ratio1:1001:100

4.4. Size of stock tank in gallonsSize of stock tank in gallons25 gallons25 gallons

1 oz / 100 gal = 1 oz / 100 gal = 75 ppm75 ppm

The Rule of The Rule of 75 75

HOW DID WE GET THIS HOW DID WE GET THIS ??One ounce (28 grams) of any One ounce (28 grams) of any

pure dry substance that will pure dry substance that will dissolve 100% in a volume of dissolve 100% in a volume of

100 gal equals 75 ppm100 gal equals 75 ppm1 oz = 28 g or 28,000 mg1 oz = 28 g or 28,000 mg

28,000 mg ÷ 379 L = 73.88 ppm28,000 mg ÷ 379 L = 73.88 ppm( 1 gal = 3.79 L( 1 gal = 3.79 L 100 gal = 379 L )100 gal = 379 L )

SolutionSolutionStep 1: Convert the ppm Step 1: Convert the ppm

recommendation to a weight basis recommendation to a weight basis using the following equation:using the following equation:

Equation 3Equation 3 Recommended ppm x dilution factorRecommended ppm x dilution factor = =

oz fertilizer/gal stock oz fertilizer/gal stock the N number (% ) of fertilizer X 75the N number (% ) of fertilizer X 75

150 ppm x 100 150 ppm x 100 = = 10.0 oz of 20-10.0 oz of 20-10-20 per gal stock10-20 per gal stock20 x 7520 x 75 (final (final solution)solution)

SolutionSolutionStep 2: Use equation 1 to Step 2: Use equation 1 to

adjust for a stock tank size of adjust for a stock tank size of 25 gallons:25 gallons:

(oz per gal stock (oz per gal stock x (# x (# gallons in stock tank) gallons in stock tank)

= Oz fertilizer per stock tank= Oz fertilizer per stock tank10.0 oz x 25 gal10.0 oz x 25 gal tank = tank = 250 oz of 250 oz of 20-10-20 in the tank20-10-20 in the tank

SolutionSolutionStep 4: Convert ounces to pounds Step 4: Convert ounces to pounds

and ounces where:and ounces where:

16 ounces = 1 pound (dry)16 ounces = 1 pound (dry)

250.0 oz per 25 gal250.0 oz per 25 gal = = 15 lbs 10 oz 15 lbs 10 oz 20-10-20 20-10-20 16 oz16 oz /lb/lb (. . . .in a 25 (. . . .in a 25 gallon stock tank)gallon stock tank)

This will give you 150 ppm with This will give you 150 ppm with a 1/100 ratioa 1/100 ratio

Each bag is 25 lbs! Each bag is 25 lbs! Remember 25 lbs x 16 ox…the Remember 25 lbs x 16 ox…the

number of bags needed = 250 number of bags needed = 250 oz/ (16 oz X 25lbs ) or 0.62 oz/ (16 oz X 25lbs ) or 0.62

bags! bags!