NPK – The symbols for the big three nutrients needed by plants.
- N is for nitrogen
- P is for phosphorus
- K is for potash
The percent of each element in a package or bottle of fertilizer is always shown in NPK order. For example a 16-16-8 fertilizer is 16%, 16% and 8% per cent potash.
In addition to the above major elements, plants need calcium, magnesium and sulfur in relatively large amounts. Needed in trace amounts (minor elements) are: iron, manganese, boron, zinc, copper, cobalt, and molybdenum.
