Fertigation, as the name implies, is the process in which fertilizers are being applied with the irrigation water: Fertilization + Irrigation. The fertilizer solutions are prepared in advance in stock tanks and the solution is then injected into the irrigation water.
The most common fertigation approaches are the quantitative approach and the proportional approach.
The quantitative approach is commonly used in open fields. The grower first decides how much fertilizer has to be applied per area (e.g. kg/ha, lbs/acre). This quantity of fertilizer is then delivered through the irrigation water.
The proportional approach is mostly used in soil-less media and sandy soils. Here, a defined quantity of fertilizer stock solution is injected into each unit of water flowing through the irrigation system (e.g. l/m3, lbs/gal).
Nutrient levels are determined by their concentration in the irrigation water. Most growers who use proportional approach, use units of ppm (parts per million) or mmol/l.