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How can liquid fertilizers be applied?

Liquid fertilizers

Written by Jaap Lubbersen | Last update: 05-02-2021

Liquid fertilizers are offered as an alternative to fixed fertilizers. The last couple of years, the use of liquid fertilizers has increased due to several advantages. They can easily be mixed and applied and generally easier to take in for plants, due to the larger contact surface because they are dissolved already. Liquid fertilizers are applied by spraying the crop with a sprayer, which makes the nutrients available almost immediately. This is useful when the plant can’t absorb fertilizers through its roots. However, liquid fertilizers require a different approach which is explained by our specialists.

Types of liquid fertilizers

A standard package of liquid fertilizers consists out of 7 or 8 different fertilizers. Our specialist can advise which package is best suitable for your cultivation and soil or substrate. The type of crop and the soil on which it is grown are important factors. The package of Fertigro liquid fertilizers consists of the following solutions:

Fertigro CN Calcium nitrate
Fertigro AN Ammonium nitrate
Fertigro KZZ Kali sulphuricum
Fertigro KFL Potassium phosphorus hydroxide
Fertigro KL-50 Potassium hydroxide
Fertigro KBL Potassium carbonate
Fertigro MSN Magnesium sulphate
Fertigro SZ-38        Nitric acid
Fertigro FZ-59 Phosphoric acid
Fertigro CC Calcium chloride
Fertigro SiL Potassium silicate
Fertifosk Potassium phosphite

Liquid substances

Calculation of nutrient solution

The method used to calculate the needed amount of liquid fertilizers is different from the one used for fixed fertilizers. The concentration of different elements in the nutrient solution is taken as a basis for the liquid fertilizers (in mmol per litre).

If a tank contains 1,000 litres in which a 100 times concentrated solution is made, it means the concentration of the elements of the solution must be multiplied 100 x 1,000= 100,000 to calculate the amount needed for the A and B tank. 
Example: 13.5 mmol of nitrate nitrogen (N03-) in the nutrient solution 13.5 x 100 x 1000 = 1.350.000 mmol = 1350 mol nitrate nitrogen in the A and B tank.

In this way, the amount needed can be calculated for each element. An example of a completed calculation scheme can be found below:



mol total1600150440120950540240









200 150 250
KFL64,944,1 150 345 195
KL-5051,334,2 455 455


Standard nutrition scheme and adjustment

Based on the research, the necessary ion ratio is determined within the roots for the plant to take in optimal nutrition. This optimal ion ratio is translated to standard nutrition solutions. These are put together in a way that the average target values are met.

During the growing process, the ratio between nutrition and the roots constantly changes (generally, changes occur faster once the growth systems are closed in comparison to growth systems with free drainage). This is often impossible to predict, because it depends on several factors such as climate, plant stadium and plant burden. Therefore, it’s crucial to regularly check the composition of the nutritional solution in the roots. This might indicate a need for adjustment of the nutritional scheme.

Mix liquid fertilizers

Liquid fertilizers can be divided into neutral, acid and lye. Incorrect mixture of these different products could lead to unintentional contamination. You should always take this into account while mixing. 

Storage of liquid fertilizers

Liquid fertilizers can be divided into neutral, acid and lye. Improper mixing of these different products can lead to unintentional contamination. This is something you should always keep in mind while mixing and storing fertilizers. Our specialists have also written an article on how to store fertilizers.

Working safely with liquid fertilizers

Liquid fertilizers are highly concentrated products. As a result, contact with the skin or eyes can have serious consequences. It is therefore very important that you are aware of the points of attention that apply to working with liquid fertilizers. 

More information about fertilizers

Do you have any questions about liquid fertilizers, or would you like advice? Then contact one of our crop care specialists, or ask your question using the form below. We'll respond within 24 hours on working days.

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Jaap Lubbersen About Jaap Lubbersen

Jaap Lubbersen is an internal crop care product specialist at Royal Brinkman and has had over 13 years of experience in glass horticulture. "As an internal product specialist, I deal with growers' issues on a daily basis. Every time again it is a challenge to seek the proper solution, in cooperation with the grower, whether it is about healthy and vibrant cultivation, legislation or safety."

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