What does NPK stand for? The NPK meaning reflects the three elements found in this fertilizer mixtures—nitrogen, phosphorus, and potassium. The three letters refer to the chemical symbols used to identify these elements:
- N for nitrogen
- P for phosphorus
- K for potassium
When plants are regularly fertilized, they receive all of the essential nutrients needed for proper growth. Studies have shown that plants receiving fertilizers are more resistant to pests and disease. Moreover, fertilizing plants also enhances the flower and leaf growth, as well as crop production.
How Components of NPK are Obtained
The three main components of NPK fertilizer represent relatively common and easy elements to obtain. So how are the components of NPK fertilizer obtained? Nitrogen represents the largest component of the air found in Earth’s atmosphere. There are several methods for isolating nitrogen from the air. For example, electrosynthesis uses electrolysis to separate hydrogen from water.
During this process, nitrogen accumulates on the electrodes that generate the electricity needed for electrolysis. Metal catalysts are sometimes used to help speed up the process of nitrogen isolation and accumulation.
Phosphorus is typically not found in isolation. Instead, it usually combines with other elements to form rocks and the fossil remains of living organisms. In order to obtain phosphorus from these sources, rocks must be mined and exposed to chemicals like acids to isolate phosphorus.
Potassium represents another common element found in Earth’s rocks and oceans. A majority of the potassium used in fertilizers is derived from evaporated saltwater from Earth’s ancient seas and oceans. Ores derived from these are mined and the potassium is separated and purified from the other elements found in these deposits.
What do the numbers on fertilizer mean? The fertilizer numbers on a package refer to the NPK ratio, which determines the ratio of nitrogen, phosphorus, and potassium in the package. Different plants often have different nutritional requirements. As a result, there are many different NPK fertilizer blends available in garden centers.
When looking at a package of NPK fertilizer, three numbers will typically be noted on the bag. These numbers specifically tell the percentage of nitrogen, phosphorus, and potassium contained in the fertilizer. For example, a 20-20-20 blend means that the fertilizer contains 20% nitrogen, 20% phosphorus, and 20% potassium. Another common blend is 16-20-18, which refers to 16% nitrogen, 20% phosphorus, and 18% potassium.
When all three micronutrients are present in the ratio, this is referred to as a complete fertilizer. However, some blends contain only one or two of these micronutrients. If one of these micronutrients is absent from the blend, then the corresponding number in the ratio will be replaced with a zero. 10-0-0 fertilizer, for instance, only contains 10% nitrogen. The absence of one or two micronutrients is known as an incomplete fertilizer.
The Use of NPK as a Plant Fertilizer
In many parts of the world, the soil used to plant crops or grow flowers often lacks one or more of these essential nutrients. In order to help plants to grow, farmers or gardeners can add these nutrients back into the soil. Because of its widespread availability, manure can be added to the soil to help provide these nutrients. Manure refers to organic matter collected from composting or animal feces.
Aside from manure, plant fertilizers are also commonly used to help provide plants with essential nutrients to help improve health, growth, and crop yield. NPK is often used as a fertilizer due to its combination of three essential nutrients:
Each of these micronutrients affect plant health in different ways.