A fertilizer is a chemical that helps plants to grow. It is used to replace the mineral salts taken by plants or removed by rain.
- Manure (Animal waste) which was the first fertilizer.
The important things in fertilizer are:
- Nitrogen (N)
- Phosphorus (P)
- Potash (K)
When fertilizer is for sale, the percentage of N, P, and K in it may be written on the bag or box, like this: 9-23-30. That means 9% N, 23% P, and 30% K.
Leafy plants need lots of N. Flowering plants need lots of P and K.
A soil test can tell how much N, P, and K is needed.
See also: Fertilizer Experiments & Background Information
Source: Wikipedia (All text is available under the terms of the GNU Free Documentation License)