Chapter 20

Fertigation in Greenhouse Production

(book excerpts)

Fertigation is the injection of fertilizers through the irrigation system. Micro-irrigation systems are well-suited to fertigation because of their frequency of operation and because water application can be easily controlled by the grower, but it can also be done with ebb-and-flow and trough bench systems. Fertigation has some specific advantages including: (1) a frequent supply of nutrients reduces fluctuation of nutrient concentration in substrate; (2) there is efficient utilization and precise application of nutrients according to the nutritional requirements of the crop; and (3) fertilizers are applied throughout the irrigated substrate volume. Nutrient characteristics such as solubility and mobility are important and irrigation water quality factors such as pH, mineral content, salinity, and nutrient solubility must be considered. The macronutrients nitrogen, potassium, phosphorus, and magnesium are the most common nutrients applied by fertigation, but micronutrients such as boron, zinc, iron, calcium manganese, and copper can also be applied through the irrigation system. In addition to fertilizers the application of other chemicals, referred to as chemigation, is also practiced. These can include-herbicides, insecticides, fungicides, fumigants, plant growth regulators, rodenticides, disinfectants, sanitizers, buffering agents, desiccants, defoliants, sprout inhibitors, and spray adjuvant.

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