This invention relates to a method and means to control an irrigation system and an apparatus for chemical input. A chemical injection apparatus interfaces with the irrigation system in an automated way to control the application of fertilizers, nutrients, pesticides, plant growth regulators and modifying agents, water conditioners, soil conditioners and additives, and water. More particularly this invention teaches a method and device for remotely operating a continuously-calibrating chemical dispensing device of a chemigation unit, and the equipment associated with data acquisition, control and injection equipment.
