Fertigation in Greenhouse Production
Preparation of Stock Solutions for Fertigation
In proportional fertigation, concentrated nutrient solutions are prepared in a number of tanks. The solutions are then injected to the irrigation water at adequate ratios. These concentrated solutions are known as “stock solutions.”
Batch Mixing
The simplest way to produce the final feed strength is to directly mix all the ingredients in a large holding tank. Accurate measurement of each ingredient (including water) will ensure great accuracy. With a moderate tank mixing, it is relatively easy to achieve excellent uniformity. This process is known as batch mixing and it is arguably the simplest, safest, and most accurate way to achieve the final dilution strength.
Automatic Dilution Systems
Most fertilizer mixing systems use a progressive dilution strategy that allows you to manually mix relatively small tanks of high strength stock solutions that are then diluted with much larger volumes of water to produce the final dilution ratio.
Dilute Blending Tank Control
With the advent of injection technologies and automation, it became possible to have a continuous process where a small open blending tank is continuously “topped up” with water and concentrated stock solutions.
Rules for Mixing Fertilizers
Most commercial greenhouse operations use a two-stock tank system for mixing fertilizers, although some systems involve three stock tanks with the third tank containing the acid or bicarbonate for pH adjustment. The first rule in mixing fertilizers is to always use high quality, water soluble “greenhouse grade” fertilizers. Second, when working with stock tank concentrates, never mix calcium containing fertilizers (e.g., calcium nitrate) with any fertilizers containing phosphates (e.g., monopotassium phosphate) or sulfates (e.g., potassium sulfate, magnesium sulfate) as discussed in the section, Criteria for Selecting Fertilizers for Fertigation.
Click on the following topics for more information on fertigation in greenhouse production.
Topics Within This Chapter:
- Introduction to Fertigation in Greenhouse Production
- Fertilizer Dosing Methods
- Pressure Differential Tank Fertigation Injection
- Venturi Fertigation Injectors
- Positive Displacement Fertigation Injectors
- Proportional Fertigation Injectors
- Electric Metering (EC/pH) Fertigation Injectors
- Calibrating Fertigation Injectors
- Criteria for Selecting a Fertigation Injector
- Design and Management Considerations for Fertigation Systems
- Criteria for Selecting Fertilizers for Fertigation
- Fertilizer Calculations for Greenhouse Crops
