Can Adblue Be Used As A Fertilizer?

Last updated on November 2nd, 2023 at 01:02 pm

Many people probably only know AdBlue from their diesel car, where AdBlue is used for exhaust gas aftertreatment.

But perhaps you have also heard that AdBlue can be used as a fertilizer?

Can Adblue Be Used As A Fertilizer?

Whether and if so, how to use AdBlue as fertilizer in the garden you will learn in this article.

Can you use AdBlue as fertilizer

AdBlue can be used pure or diluted with water as a slow release fertilizer in the garden or for lawns. This is because AdBlue consists of 32.5% urea, which in turn contains 46% nitrogen and makes plants grow better and promotes yield and green color.

Can you fertilize with AdBlue?

Commercially available AdBlue can be used for fertilizing without any problems, as it has a high nitrogen content and thus primarily promotes plant growth and yield.

In addition, the nitrogen in AdBlue* ensures that the plants’ metabolism and photosynthesis (i.e. leaf greening) are stimulated.

More precisely, AdBlue is a 32.5 percent urea solution (i.e., a mixture of 32.5 percent pure urea and 67.5 percent demineralized water), the purity and quality of which is ensured by various ISO and DIN standards.

The urea contained in AdBlue, in turn, consists of 46% pure nitrogen, which is also contained in other, conventional nitrogen or complete fertilizers.

Can you fertilize with any AdBlue?

Since AdBlue is a registered trademark, all agents labeled “AdBlue” must meet certain requirements and tests (including, for example, this one from Hoyer*). This means that all AdBlue agents have exactly the same composition and quality and can therefore be used for fertilizing.

So which type of AdBlue you have available and use for fertilizing does not matter. The dosage and effect should always be the same.

Is AdBlue toxic to plants?

In general, AdBlue* is not toxic to plants, as it is simply a mixture of urea and water. Urea, as the name suggests, is also present in human urine. Thus, AdBlue can be used for fertilizing plants if handled carefully and dosed correctly.

However, as with other conventional fertilizers, overfertilization can occur in the worst case. This is the case when too much of AdBlue is used. Here you can find out how to dose AdBlue correctly.

Although AdBlue* is not toxic, it can cause irritation if it comes into direct contact with the skin, eyes or leaves or stems of plants.

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Therefore, you should be careful not to let AdBlue come into contact with your skin or eyes, or smell it.

When fertilizing your plants, you should also make sure that you apply the AdBlue directly to the soil, as contact with leaves may cause them to become irritated or slightly yellow.

Why can you use AdBlue as a fertilizer?

AdBlue* is a slow-release fertilizer that acts in a similar way to liquid manure. This means that the urea contained in AdBlue is converted into nitrate after several conversion steps. Nitrate is ultimately absorbed by the plants through the roots and used to metabolize or build protein.

The urea or nitrogen contained in AdBlue thus provides the basis from which nitrate, which is absolutely necessary for plant growth, is made.

However, nitrogen losses can occur during the metabolism of urea to nitrate, as the intermediate product ammonia is gaseous and can therefore escape into the atmosphere.

However, these nitrogen losses can be minimized by the correct application of AdBlue and are insignificant in the comparatively small home garden.

Why use AdBlue instead of pure urea for fertilizing?
In contrast to pure urea or fertilizer urea, AdBlue is suitable for fertilizing especially for beginners or for trying out.

This is because AdBlue can also be purchased in relatively small quantities (from 1 liter bottles), while fertilizer urea is usually only available in 25kg bags.

How do you fertilize with AdBlue?

When fertilizing with AdBlue (e.g. with this commercially available version*), the procedure should be considered in addition to the right weather conditions. You can read about how to fertilize with AdBlue in the following sections:

Correct weather conditions

To make the application of AdBlue as effective as possible and to reduce possible nitrogen losses as much as possible, you should pay attention to the right weather conditions when applying AdBlue in the garden:

Sufficient moisture in the soil (a slightly moist soil or light rainfall after fertilizing with AdBlue is ideal).
Low, rather cool temperatures and no to little sunlight
A soil pH less than 7 (if the soil pH is greater than 6.5, then you should work the AdBlue in very lightly with a rake or rake, or water the soil lightly)
Also, be careful not to apply AdBlue directly over leaves or stems, as they can become irritated and look yellow or slightly burned.

Fertilize with AdBlue

You can fertilize your garden with AdBlue in two different ways: on the one hand undiluted e.g. with a pressure sprayer (like this one from Gardena*) and on the other hand mixed with water.

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Use AdBlue undiluted with a pressure sprayer*.
AdBlue is easiest to use in pure, undiluted form for fertilizing. However, since AdBlue is liquid, it is quite difficult to fertilize evenly with the bottle.

Therefore, it is recommended to apply AdBlue either into a watering can* with a sprayer or, even better, with a pressure sprayer.

For this purpose, AdBlue can be added undiluted to the watering can or pressure sprayer and the fertilization applied.

Mix into the water
AdBlue can also be mixed into the water for fertilizing and then applied with a watering can, preferably with a sprayer, or a pressure sprayer.

However, when AdBlue is mixed with irrigation water, the urea contained in the AdBlue is diluted, weakening the fertilizing effect.

If you mix AdBlue and water in equal parts, e.g. dilute one liter of AdBlue with one liter of irrigation water, the fertilizing effect will be halved.

AdBlue dosage as fertilizer

Between 15-30 grams of AdBlue* per m² should be used for fertilizing. 1 liter of AdBlue can thus be used for fertilizing the equivalent of 33-65 m² of garden area.

The lower range of AdBlue dosage, i.e. 15 grams of AdBlue per square meter, can be used for a first attempt or when perhaps other fertilizers have already been applied.

The upper range of AdBlue dosage, i.e. about 30 grams of AdBlue per square meter, can be used if you already have experience with fertilizing with AdBlue and have not yet fertilized (heavily) with other fertilizers.

The right AdBlue mixing ratio

AdBlue can, but does not have to be mixed with water. However, when AdBlue is mixed with water, it is much easier to apply it to larger areas. As long as one does not exceed the recommended total amount of AdBlue per m², the mixing ratio of AdBlue and water can be freely chosen.

The more water is used, the more watery and less concentrated the mixture will be, but then there will be more of it and it may be easier to spread.

In the following table you will find different quantities of AdBlue for different garden sizes between 10 and 100 square meters, where I have assumed a medium fertilization, with about 23 grams of AdBlue per m².

You can determine the mixing ratio of AdBlue with water yourself. That means you can add as much water as you like to the respective amount of AdBlue.

Area sizeAmount of AdBlue (approx.)Quantity water
10 m²230 ml (0,23 l)Any amount of water
20 m²460 ml (0,46 l)
30 m²690 ml (0,69 l)
40 m²920 ml (0,92 l)
50 m²1150 ml (1,15 l)
60 m²1380 ml (1,38 l)
70 m²1610 ml (1,61 l)
80 m²1840 ml (1,84 l)
90 m²2070 ml (2,07 l)
100 m²2300 ml (2,30 l)

AdBlue as lawn fertilizer?

AdBlue* can be used both in the entire garden and specifically as a lawn fertilizer, because the urea contained in AdBlue consists largely of nitrogen, which in turn is also contained in conventional nitrogen or complete fertilizers.

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AdBlue contributes to better lawn growth and, above all, ensures a lush green, as the nitrogen contained in AdBlue also boosts photosynthesis (i.e. green formation) in the lawn.


The correct AdBlue mixing ratio for lawns.
For fertilizing lawns with AdBlue*, the same dosage can be used as for fertilizing other garden areas, i.e. between 15-30 grams of AdBlue per square meter of lawn. One liter of AdBlue can therefore be used to fertilize the equivalent of 33-65 m² of lawn.

However, there is no prescribed mixing ratio for AdBlue with water. As long as the recommended maximum amount of AdBlue per square meter is not exceeded, AdBlue can be mixed with any amount of water.

Advantages of AdBlue as fertilizer

The use of AdBlue as a fertilizer has several advantages:

  • Easy application
  • Inexpensive or similar price to other nitrogen fertilizers (AdBlue available e.g. here*)
  • Very effective
  • Long-term effect
  • Does not change the pH-value of the soil, because the contained uric acid is slightly basic but this does not affect the soil pH-value

Disadvantages of AdBlue as fertilizer

However, there are some disadvantages to fertilizing with AdBlue that should be considered:

  • Expensive compared to pure fertilizer urea (available here*).
  • Soil must be moist or rainfall must follow quickly after fertilizing
  • AdBlue is not a complete fertilizer, which means it contains only nitrogen but no phosphorus or potassium
  • AdBlue in liquid form is more difficult to apply than other fertilizers (or fertilizer urea) in solid form
  • Depending on weather and volume, up to 80% of the nitrogen can outgas after application of AdBlue in the form of ammonia, which is harmful to the environment (however, with proper application and on small home garden plots, this is harmless)


  • James Jones

    Meet James Jones, a passionate gardening writer whose words bloom with the wisdom of an experienced horticulturist. With a deep-rooted love for all things green, James has dedicated his life to sharing the art and science of gardening with the world. James's words have found their way into countless publications, and his gardening insights have inspired a new generation of green thumbs. His commitment to sustainability and environmental stewardship shines through in every article he crafts.

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