FERTILIZERS AND PLANT NUTRIENTS

What does fertilizer "analysis" mean?

All fertilizers have three numbers on the label which indicate the fertilizer analysis, or "percentage by weight" of nitrogen, phosphorus and potassium, in that order.
       
Therefore, a 50 pound bag of fertilizer labeled 20-10-5 would contain 20% nitrogen (10 pounds), 10% available phosphates (5 pounds), and 5% soluble potash (2.5 pounds). 
See the calculations below:

50 pound bag of 20-10-5 fertilizer:
  20% nitrogen (.20 x 50 lbs = 10 lbs)
  10% available phosphates (.10 x 50 lbs = 5 lbs)
    5% water soluble potash (.05 x 50 lbs = 2.5 lbs)

Furthermore, this product would be considered a "complete" fertilizer, since all three nutrients are present.
  
An "incomplete" fertilizer would have a label like 0-0-60 or 46-0-0, since it would only have one of the three major nutrients present. Another example of an incomplete fertilizer would be 0-20-20, since one of the three nutrients is missing.
  
Fertilizers also have "ratios" which indicate the relative amounts of nutrients to each other. For example, a 10-10-10 fertilizer is a 1-1-1 ratio, and a 20-10-5 fertilizer is a 4-2-1 ratio.
  
Ratios can be helpful when looking for the "right mix" for a certain type of plant or situation.  For example, vegetable gardens often call for a 1-2-1 ratio, which would translate into a 5-10-5 or 10-20-10 fertilizer.  Most trees like a 2-1-1 ratio, which would be a fertilizer product such as 10-5-5 or 20-10-10.  Lawns prefer a 3-1-2 ratio fertilizer, so a fertilizer product with 30-10-20 on the label would be a good ratio match.
  
High analysis fertilizers (those with larger numbers on the label) would be applied at a lower rate to yield the same results.  In other words, 5 lbs of a 20-20-20 fertilizer would yield the same amount of actual nutrients as 10 lbs of a 10-10-10 fertilizer.

ALWAYS READ AND FOLLOW
LABEL DIRECTIONS!
   

What do the 3 numbers on the fertilizer bag mean?

Answer: N - P - K

These are the "major nutrients"
Nitrogen - Phosphorus - Potassium

NITROGEN (N) - the Nitrogen percentage is the first number on the label

Example: 10-10-10

Nitrogen is a primary nutrient that really makes plants "grow."  When you put fertilizer on your lawn, most of the "green-up and grow" comes from the nitrogen.

Phosphorus is a primary nutrient that encourages rooting, blooming and fruit production in plants.

Potassium helps plants resist disease and aids in winter hardiness.("K" is the symbol for "kalium" or potash, and is commonly used to represent potassium)

Secondary Nutrients
Secondary nutrients also play an important role in plant growth.  The 3 secondary nutrients are Calcium (Ca), Magnesium (Mg) and Sulfur (S).

Essential Elements
The essential elements are basic to plant growth, and need to be mentioned here, even though they aren't commercially available fertilizers.  The 3 essential elements are Carbon (C), Hydrogen (H) and Oxygen (O).  Plants obtain these elements from carbon dioxide (CO2) and water (H2O).

Macronutrients
When you group the essential elements with the major nutrients and secondary nutrients, you end up with the 9 macronutrients: Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorus, Potassium, Calcium, Magnesium, and Sulfur: C, H, O     N, P, K    Ca, Mg, S

Minor Elements
Nutrients needed by plants in lesser amounts are known as the minor elements.  These include Iron (Fe), Boron (B), Manganese (Mn), Copper (Cu), Chlorine (Cl), Molybdenum (Mo), and Zinc

Remembering it all
YIKES!
How can you possibly remember everything?
Simple . . . start with the name of a famous restaurant manager in the table below:

• fertilizing daffodils
• liming
• soil
• soil amendments
• soil pH
• soil tests