Hort 4040
Calculation Homework Problems (4 Problems)
1.Your new boss suggests that you adjust your fertility program. He hands you a bag of 15-17-20 and tells you to apply a 175 ppm N solution to the pansies. You own a Dositron injector currently set at 1/100. You are given a 5 gallon bucket that serves as the stock tank. Show me the calculations you need to perform to have the correct amount of fertilizer placed in the stock tank to deliver 175 ppm N.
2.Weeks later your boss tells you to change over to a “BloomBooster” fertilizer: 25-20-15. He wants a 300 ppm solution applied to the mums. You are given a stock tank capable of holding 5 gallons. The injector set up is the same. How much fertilizer is put into the stock tank?
3.Your bossputs up series of“high tunnels” for pansies in the middle of an open field to increase fall production and make money! The weather is cold, nasty and you’re late for YOGA CLASS! She hands you a “Hozon” siphon proportioner that has a mixing ratio of 1/ 15. She shows you an old 20 gallon pig trough to be used for the stock tank for these structures. Then she tells you she wants a 125 ppm solution of calcium nitrate, 15-0-0-15, (N–P-K-Mg) applied to the pansies pronto! How much fertilizer do you put in the stock tank?
4.Mostly frozen, you decide your boss is a real jerk, you hate pig troughs and you want something better in a career than his pansy operation.....so you quit and land a good job in a big greenhouse firm in South Georgia. It’s warmer and you are happy. Your new boss over-hears you complaining about the old boss and ahe smiles really big! She pulls you aside and says “I have an easy fertilizing task for you with all modern equipment....no pig troughs here!” She shows you a 150 gallon steel stock tank and a brand new high quality “Smith” injector with a 1 to 200 ratio capability. She tells you to set the ratio at 1 to 150. She instructs you that she needs a 200 ppm solution of N applied to two acres of marigolds. Inquiring, you ask if you need to fill the stock tank all the way. He smiles really, really big and tells you that it will likely take two complete stock tanks to get through the day’s job. The application rate is 0.25 gallons per sq ft. She comes back in a few minutes later and says “Let’s get the fertilizer bags!” She watches as you climb up and pull bags from a huge storage bin. Not wanting to appear primitive and backwards, how many 25 lb bags of 20-20-20 will you pull off the shelf to accommodate the job? How much dry fertilizer will you have left over that needs to be resealed in a plastic bag? How many stock tanks will you need to plan for?
Remember: List the 4 things you need:
Recommended concentration in ppm
Injector ratio
Fertilizer analysis (remember: 20-10-20 = 20% N = 20!
Stock tank size
Use this equation for the rule of 75:
(Recommended ppm N) x (Injector ratio) = ounces per gallon stock solution
(% N from Bag) x 75
Now multiply that answer by the size of your stock tank. = ounces you need to put in the stock tank!
1 acre = 43560 sq. ft. There are 16 oz in a pound. There are 25 lbs fertilizer to a bag.
Now use the answer sheet below and check your answers using the web downloadable fertilizer calculator!
Hort 4040 – Fertilizer Problems
Answer Sheet
Problem 1
( ) x ( ) = ( ) Ounces per gallon stock solution
( ) x 75
( ) x ( ) = ( ) Ounces of fertilizer to put into the stock tank
Problem 2
( ) x ( ) = ( ) Ounces per gallon stock solution
( ) x 75
( ) x ( ) = ( ) Ounces of fertilizer to put into the stock tank
Problem 3
( ) x ( ) = ( ) Ounces per gallon stock solution
( ) x 75
( ) x ( ) = ( ) Ounces of fertilizer to put into the stock tank
Problem 4
( ) x ( ) = ( ) Ounces per gallon stock solution
( ) x 75
( ) x ( ) = ( ) Ounces of fertilizer to put into the stock tank
( ) Ounces / 16 oz/pound = ( ) pounds of fertilizer / 25 lbs per bag = ( ) Bags!
Next determine production area: ( ) acres x 43560 sq ft/acre = ( ) sq ft of production.
( ) sq ft of production x ( ) gallons per sq. ft applied = ( )Total gallons needed!
( ) Gallons of stock x ( ) injector ratio = ( ) total gallons possible from stock tank.
( ) total gallons possible - ( ) total gallons needed = ( ) gallons (short or in excess of what you need)! Did we do this operation using one or tanks? Was the owner right?
Name ______
Hort 4040 – Fertilizer Problems
The Answer Page
Problem 1
( 175 ) x (100 ) = ( 11.67 ) Ounces per gallon stock solution
( 15) x 75
( 15.55 ) x (5gal stock ) = ( 77.77) Ounces of fertilizer to put into the stock tank
Problem 2
( 300 ) x ( 100 ) = ( 16 ) Ounces per gallon stock solution
( 25 ) x 75
( 16 ) x ( 5 ) = ( 80 ) Ounces of fertilizer to put into the stock tank
Problem 3
( 125 ) x ( 15 ) = ( 1.667 ) Ounces per gallon stock solution
( 15 ) x 75
( 1.667 ) x ( 20 ) = ( 33.3 ) Ounces of fertilizer to put into the stock tank
Problem 4
( 200 ) x ( 150 ) = ( 20 ) Ounces per gallon stock solution
( 20 ) x 75
( 20 ) x ( 150 ) Stock Tank Size = ( 3000 ) Ounces of fertilizer to put into the stock tank
( 3000 ) oz needed / 16 oz per pound = ( 187.5 ) pounds / 25 lb/bag = (7.5 )Bags needed per tank.
( 2 ) Acres x 43560 sq ft/acre = ( 87120 ) sq, ft to be fertilized x ( .25 fraction of gallon) applied per sq, ft. = ( 21780 ) Total number of gallons final product out the hose we need for that task is 21780!.
The total gallons final product per tank that could possibhly be made.given that tank size is (150 )Gallons stock x (150 ) injector ratio = (22,500 gallons)
So if we subtract 21780 from 22,500, (22,500-21780 = 720 gallons of potential fertilizer solution) ….we have a remainder of 720 potential gallons of fertilizer solution we could use elsewhere. This means we did not use the whole tank! 21780/22,500 = 0.968 x 100 or 96.8 % of the tank was used. 0.32 is left in the tank.
The owner tried to test you…and she succeeded!