The chemigation (Fertilization)

With a simple definition, the application of plant nutrients (liquid or solid fertilizers) to the soil or plant root area with irrigation water via irrigation systems. 
The procedure includes the introduction of chlorine, acid, or other chemicals used for the cleaning of water or for the purification of some elements of irrigation systems. 

 Has specific names according to type of chemical:
- Fertigation, plant nutrients-fertilizers,
- fungal, fungicides
- Insecticide
- Herbulation is used to show that herbicides are applied together with irrigation water.
• The use of chemicals or fertilizers with a drip irrigation system should not cause flushing or wear.
Fertilizer equipment
Fertilizer equipment can be divided into two types
• Vacuum-operated pumps
• Systems based on pressures
- Closed tanks (by-pass connection),
- Venturi part and open fertilizer tan
Direct connection
By-pass connection
 Pumps (fertilizer pumps)
Fertilizer tank
In drip irrigation systems, plant nutrients are mixed with water for irrigation. For this purpose, liquid fertilizer is used.
 The quantity of liquid fertilizer calculated in accordance with the size of the irrigation surface is placed in the fertilizer tank in the control unit.
 Fertilizer tank is connected to the main pipe in two points using a valve hose on it. One is to supply water to the fertilizer tank and the other to exit water.
• In the fertilizer tank, the inlet hose continues to the bottom of the tank. The outlet pipe starts at the top of the tank.
• The vent valve is located at the top of the outlet pipe.
• In the meantime, a control valve is installed on the main pipe before the entry point into the fertilizer tank. Therefore, it is prevented that fertilizer mixed with water is directed towards the source of water.

The method of connection of the reservoir fertilizer to the irrigation system through the bypass method.
When fertilizing, the dose is not the same, the dose decreases towards the end of the application,
- The concentration control of fertilizer in the solution is limited,
- Not suitable for light soils and cultivation without soil,
- Not suitable for automation.
Fertilizer application
There must be a manometer on the main pipe before and after the entry point.
• An additional valve is placed on the main pipe to create a pressure difference between the two points.
• When manure is applied, the valve on the main pipe is partially closed, and the inlet and outlet valves of the fertilizer containers are opened. Therefore, some of the water in the main pipe enters the fertilizer tank, mixes with liquid fertilizer and returns to the main pipe.

Fertilizer application time
In the drip irrigation systems, the fertilizer application time should be 75-80% of the irrigation time.
In the remaining time, it is ensured that the fertilizer that can remain in the dripper flow path is washed out with irrigation water. This is because if the fertilizer solution remains in the dripper after irrigation, it may cause chemical accumulation and a partial blockage of the dripper.
Application of fertilizers in a short time can negatively affect on the distribution of fertilizers in the whole area.
Venturi systems
• Works on the Venturi principle.
• Contraction in the flow cross-sectional area increases the speed of the water and causes a pressure difference. This causes the solution to be sucked into the irrigation water from an open tank.
• Flow can be controlled using a valve.
• A very simple, feasible and cheap system.
• However, there are certain limitations. Pressure losses in the Venturi cross-section are very high, roughly 1/3 of the operating pressure.
• Requires high pressure.