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How to irrigate plants and apply fertilizer at the same time

If you take care of your soil, the soil will take care of your plants

This is the season where Knapsack sprayer parts are highly sought out in Kenya. Knapsack sprayers are used to apply fertilizer and pesticides to plants. During this application process, many sprayers break down due to mishandling and which results in you buying new sprayers or repeating the same process of buying spare parts again next year. There is however a better and more efficient solution called Fertigation that can be used to apply fertilizer on your field.

Fertigation is delivering fertilizers to plants through irrigation. This system allows you to supply nutrients to plants without having any wastage. This is done by releasing small doses of fertilizer in exact amounts to ensure the crop gets the right amount of nutrients. While fertigation systems will help you avoid the hassles of buying Knapsack sprayer parts, the primary purpose of fertigation is to save the cost in applying fertilizer.

Which Fertigation system should I use?

Several techniques have been developed for applying fertilizers through the irrigation systems and many types of injectors are available on the market.

Venturi  Kit-This is based on the principle of the Venturi tube. A pressure difference is needed between the inlet and the outlet of the injector. It is installed on a bypass arrangement placed on an open container with the fertilizer solution. The rate of injection is very sensitive to pressure variations, and small pressure regulators are sometimes needed for a constant ejection. Friction losses are approximately 1.0 bar. The injectors are made of plastic in sizes from to 2 inches and with injection rates of 40–2 000 litres/h. They are relatively cheap compared to other injectors.

Fertilizer Tank– This is a cylindrical, epoxy coated, pressurized metal tank, resistant to the system’s pressure, and connected as a bypass to the supply pipe of the head control. It operates by differential pressure created by a partially closed valve, placed on the pipeline between the inlet and the outlet of the tank. Part of the flow is diverted
to the tank entering at the bottom. It mixes with the fertilizer solution and the dilution is ejected into the system. The dilution ratio and the rate of injection are not constant. The concentration of fertilizer is high at the beginning and very low at the end of the operation.

Piston Pump– This type of injector is powered by the water pressure of the system and can be installed directly on the supply line and not on a bypass line. The system’s flow activates the pistons and the injector is operated, ejecting the fertilizer solution from a container, while maintaining a constant rate of injection. The rate varies from 9 to 2 500 litres/h depending on the pressure of the system and it can be adjusted by small regulators. Made of durable plastic material, these injectors are available in various models and sizes. They are more expensive than the Venturi-type injectors.

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What are the benefits of fertigation?

Fertigation has the following benefits;

  • Controlled application of nutrients and water.
  • Increased flexibility of fertilizer application.
  • Allows better timing of application correlated with crop growth stage.
  • Allows small dosage application.
  • Minimizes leaching and negative environmental impact.
  • Increased water use efficiency.
  • Increased fertilizer use efficiency.
  • Potential to reduce fertilizer inputs, reducing production costs.
  • Reduce foliar disease by minimizing leaf wetness.
  • Reduce weeds because the fertilizer is only applied to crop.

What should I watch out for in Fertigation Systems?

Fertigation is awesome, there are however things that you need to watch out for e.g;

  • You will need to manage your farm well.
  • Investment in appropriate injection equipment although for small farms the investment will not be high.
  • Fertilizer source must be water soluble
  • Be cautious of precipitation reactions with fertilizer components.

Using fertilizer injector systems to apply fertilizer is a great way of providing nutrients to plants. The method enhances the proper use of resources as it’s possible to irrigate plants and apply fertilizer at the same time. This saves time and money and ensures plants get the proper nutrients to keep them healthy.

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  • Joseph Boit

    Joseph is the founder of Graduate Farmer, a Kenyan online platform that provides resources and tools to help farmers improve their agricultural practices and increase their productivity. Joseph is a passionate follower of Christ and farmer who loves to use technology to make a positive impact on people's lives.



  1. Very educative. Everyday we get to learn the alternative of doing this. these alternatives help us save and improve our farming methods.Thank you for that.

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