Fertilizer Labels Fertilizer Labels and Applicationand Application

ObjectiveObjective

Reading fertilizer labels and calculating Reading fertilizer labels and calculating fertilizer application formulas.fertilizer application formulas.

Major Ingredients1. Most commercial fertilizers have 3 numbers

on the front label, separated by dashes. For example: 5-10-5.

2. This is the fertilizer analysis or percentage by weight of the 3 major nutrients plants need: nitrogen, phosphorus and potassium, in that order.

3. These are abbreviated as N-P-K.

Get out your Calculator and Analyze1. If you purchased a 10 pound bag of fertilizer labeled 5-10-5,

it would contain… 5% nitrogen 10% phosphorus 5% potassium. The remaining 80% could be comprised of other nutrients and

filler.

2. How many pounds of NP and K does it contain? .5 lb. nitrogen 1 lb. phosphorus .5 lb. potassium The remaining 8 lbs could be comprised of other nutrients and

filler.

1st Number = Nitrogen1. The first number gives the concentration of

nitrogen in the product. 2. Nitrogen encourages foliage growth, among

other benefits. 3. A 5-10-5 fertilizer would contain 5% nitrogen

by weight. 4. For every pound of fertilizer applied there is

really only .05 pounds of nitrogen. (The 10 pound bag mentioned would contain .5 lb.

nitrogen)

2nd Number = Phosphorous1. The middle number refers to the concentration

of phosphorous. 2. Phosphorous contributes to many fundamental

plant processes such as rooting and setting flower buds.

3. A 5-10-5 fertilizer would contain 10% phosphorous by weight or .1 pounds of phosphorous. (The 10 pound bag mentioned above would

contain 1 lb. of phosphorus.)

3rd Number = Potassium1. The final number states the concentration of

potassium.

2. Potassium contributes to the overall health and vigor of plants.

3. Again, a 5-10-5 fertilizer would contain 5% potassium by weight or .05 pounds of potassium. (The 10 pound bag mentioned above would

contain .5 lb. potassium.)

Complete Fertilizers

1. Fertilizers that contain all three major nutrients are considered complete fertilizers.

2. There are specialized fertilizers which are called incomplete because they lack one or more major nutrients such as a fertilizer labeled 0-20-20.

Fertilizer Label1. Some information is required by law

to be on the fertilizer bags:1. Net Weight2. Brand and grade of fertilizer3. Guaranteed analysis of each

nutrient in fertilizer4. Name and address of

manufacturer

Other Valuable Information Some manufacturers add the following

on the bag as well: % of water insoluble nitrogen Potential acidity Salt index Source of carrier % of minor elements Calculation rates How to calibrate spreaders

Reading a Fertilizer LabelReading a Fertilizer Label

N- 24 % P- 5 % K- 11 % Remaining 60% is

other nutrients and filler.

Analyze This! Analyze This! What do you know from the bag?What do you know from the bag?

N: 24 %

P: 6 %

K: 12 %

Use: Lawn Fertilizer

How much fertilizer do I apply?

Recommended N Rate Area of Sq Ft% of N in Fertilizer 1,000X

Write as a decimal Example: 25% = .25

Could be N P or K

Lets try!Lets try! We have a grass lawn that needs to be fertilized We have a grass lawn that needs to be fertilized

and Jake has found a bag of 16-8-8 in our garage. and Jake has found a bag of 16-8-8 in our garage. If we need to put 1 pound of nitrogen per 1,000 sq If we need to put 1 pound of nitrogen per 1,000 sq ft of our 3,000 sq ft lawn, how much fertilizer do ft of our 3,000 sq ft lawn, how much fertilizer do we need to apply?we need to apply?

Recommended N Rate Area of Sq Ft% of N in Fertilizer 1,000X

1------.16

X3,000--------1,000

= 6.25 X 3 = 18.75 lbs of fertilizer

Check for understanding Complete the practice question on your worksheet.

1.Susie has a grass lawn that needs to be fertilized, she has found a bag of 14-18-12 in her garage. If she needs to put .5 pound of potassium per 1,000 sq ft of her 5,500 sq ft lawn, how much fertilizer does she need to apply?

22.88 lbs (Round up to 23 lbs)

2.Using the previous question figure out how much nitrogen has been applied to the lawn (use the formula below).

N= Recommend P rate X % of N in % of P in fertilizer fertilizer

Check your work: N= __.5__ = 4.16 X .14 = 0.58 lbs of Nitrogen

.12

3. Jack and Jill went up the hill and noticed the grass was very yellow. Which fertilizer would be best for them to use, 12-12-12, 28-14-14 or 4-16-4?

28-14-14

Why? Nitrogen is used to help promote lush green

foliage growth, the 28-14-14 fertilizer is the highest in nitrogen.

4.Using the fertilizer you selected in the question above determine how much fertilizer they need to apply. They want to apply 1 pound of nitrogen per 1,000 sq ft and the hill is 8,888 sq ft.

32 lbs of 28-14-14 fertilizer.

Practice Reading the LabelPractice Reading the Label In the boxes on your worksheet please provide In the boxes on your worksheet please provide

the following information for each fertilizer the following information for each fertilizer placed on the tables around the class…placed on the tables around the class… Net WeightNet Weight Brand and grade of fertilizerBrand and grade of fertilizer Name and address of manufacturerName and address of manufacturer NPK percentageNPK percentage One Secondary nutrient and %One Secondary nutrient and % One Micronutrient and %One Micronutrient and %