Fertigation is the injection of fertilizers, used for soil amendments, water amendments, and other water-soluble products into an irrigation system. Fertigation is related to chemigation, the injection of chemicals into an irrigation system. The two terms are sometimes used interchangeably, however, chemigation is generally a more controlled and regulated process due to the nature of the chemicals used. Chemigation often involves insecticides, herbicides, and fungicides.

Fertigation is practiced extensively in commercial agriculture and horticulture. Fertigation is also increasingly being used for landscaping as dispenser units become more reliable and easier to use. Fertigation is used to add additional nutrients or to correct nutrient deficiencies detected in plant tissue analysis. It is usually practiced on the high-value crops such as vegetables, turf, fruit trees, and ornamentals.