Fertilizer Injectors

• This device inject small amount of concentrated liquid fertilizer directly into the water lines so that greenhouse crops are fertilized with every watering.
• Fertilizer injectors are of two basic types: Those that inject concentrated fertilizer into water lines on the basis of the venture principle and those that inject using positive displacement.

A. Venturi Principle Injectors

• Basically these injectors work by means of a pressure difference between the irrigation line and the fertilizer stock tank.

a) The most common example of this is the hozon proportioner.

b) Low pressure, or a suction, is created at the faucet connection of the Hozon at the suction tube opening. This draw up the fertilizer from the stock tank and is blended in to the irrigation water flowing through the Hozon faucet connection.

c) The average ratio of Hozon proportioners is 1:16.However, Hozon proportioners are not very precise as the ratio can vary widely depending on the water pressure.

d) These injectors are inexpensive and are suitable for small areas.

• Large amounts of fertilizer application would require huge stock tanks due to its narrow ratio.

B. Positive Displacement Injectors

• These injectors are more expensive than Hozon types, but are very accurate in proportioning fertilizer into irrigation lines regardless of water pressure.
• These injectors also have a much broader ratio with1:100 and 1:200 ratio being the most common. Thus, stock tanks for large applications areas are of manageable size and these injectors have much larger flow rates.
• Injection by these proportioners is controlled either by a water pump or an electrical pump.
• Anderson injectors are very popular in the greenhouse industry with single and multiple head models. Ratios vary from 1:100 to 1:1000 by means of a dial on the pump head for feeding flexibility. Multi head installations permit feeding several fertilizers simultaneously without mixing. This is especially significant for fertilizers that are incompatible (forming precipitates, etc.) when mixed together in concentrated form.
• Dosatron feature variable ratios (1:50 to 1:500) and a plain water bypass.
• Plus injectors also feature variable ratios (1:50 to1:1000) and operates on water pressure as low as 7 GPM.
• Gewa injectors actually inject fertilizer into the irrigation lines by pressure. The fertilizer is contained in a rubber bag inside the metal tank. Water pressure forces the fertilizer out of the bag into the water supply. Care must be taken when filling the bags as they cantear. Ratios are variable from 1:15 to 1:300.
• If your injector is installed directly in a water line, be sure to install a bypass around the injector so irrigation of plain water can be accomplished.