Fertilizer refers to nutrients added to soil in order to facilitate plant growth.
The main ingredients in fertilizer are nitrogen, phosphorus, and potassium. Plants need fairly large amounts of these nutrients and continuous growing and harvesting will deplete the soil of these if they are not replaced.
There are also many "micronutrients", or trace elements, that are sometimes included in prepared fertilizer mixes.
Fertilizers can be man-made from chemical or organic sources, or natural products (typically composted) added to the soil. Perhaps the most familiar of the "natural" fertilizers is animal manure.
- List of gardening topics
- Permaculture - Permanent agriculture
- Soil fertility