In the garden, our quest to keep everything neat and tidy sometimes makes it difficult for soils maintain their important nutrients - hence the need to augment with fertilizers.
What is a Fertilizer?
Simply put, fertilizer is plant food. It comes in thousands of varieties which may differ by source, chemical composition, type, and quickness.
Virtually anything that you add to a soil that contains the essential nutrients of plant life can technically be called a fertilizer.
Source
Fertilizers can be man-made or organic in source. Man-made types are manufactured from non-living chemical sources. They tend to be less expensive, stronger in composition and usually faster acting.
Organic fertilizers are derived from animal or plant life. They often work slower, come in weaker strengths, and tend to be more expensive. However, they have the benefit of being better for the environment and ultimately, our health.
Composition
For proper growth plants require 16 essential nutrients. Of these, three, Hydrogen, Carbon and Oxygen are obtained by the plant through the air, the sun and from water.
The next three, Nitrogen, Phosphorus and Potassium are called the Major nutrients because they are used by plants in large quantities.
When you look at any fertilizer product, you will notice three numbers in this format N-P-K.
The first number is the percentage of the product that is Nitrogen
The second number is the percentage of the product that is Phosphorus
The third number is the percentage of the product that is Potassium
The remaining contents of the product are inert ballast or filler.
By knowing what we want the fertilizer to do, we can then choose the appropriate product. For example, for cedar hedges and other plants with lots of greenery, it is obvious that we would want to provide them with a fertilizer that helps produce green growth. That is, a fertilizer with a high first number - Nitrogen.
Complete vs Incomplete
Fertilizers that have all three of the major nutrients are called Complete fertilizers. Products that are missing one or more of major nutrients are referred to as incomplete
Balanced vs Unbalanced
Fertilizers that have the same percentage of each nutrient are called Balanced. Fertilizers that have varying percentages of the major nutrients are referred to as UnBalanced.
These terms don't mean much but they do give you a frame of reference when evaluating the different products on the market.
The Other 10 Nutrients
While we have discussed Nitrogen, Phosphorus and Potassium already, there are 10 other nutrients that you need to be aware of. The Secondary nutrients are Calcium, Sulphur and Magnesium. They are used by plants in small quantities.
The Micro or Trace elements are used by plants in minute quantities but are still essential to their overall good health. The trace elements include Boron, Iron, Chlorine, Manganese, Zinc, Copper and Molybednum.
Type/Form
Fertilizer products are available in a number of different types or forms. These include:
Each has its particular advantages and disadvantages. For example, Granular products can be either fast-acting or slow release, while liquid products usually act quickly but do not last. Thereby, more frequent applications may be required.
Speed
As we just mentioned, fertilizers can be fast-acting or slow release. Fast-acting products release their nutrients quickly, over a short period of time, thereby helping plants grow as soon as possible.
Slow-release products deliver their nutrients to the soil slowly, over a long period of time. One isn't better than the other, it just depends upon your application.