Guardian Nitrogen

What is Guardian?

When you apply Guardian, you're applying a nitrogen source with inhibitors that delay the natural course of the soil nitrogen cycle.

The urease inhibitor prevents hydrolysis by neutralising urease enzymes for up to two weeks. Thus, urease inhibitor helps minimise volatilisation and loss above ground, allowing valuable time for rainfall and irrigation to work Guardian nitrogen into the soil, where it benefits your plants.

In addition, Guardian fertiliser includes DIDAN, which prevents nitrification for up to 16 weeks. As a result, your nitrogen fertiliser is held in the ammoniacal form longer, as a cation naturally held to the soil and organic matter exchange sites.

Guardian holds nitrogen in the stable ammonium form, protecting your fertiliser investment from denitrification and leaching - protection that benefits both the environment and your bottom line.

Urease Inhibitor

Benefits of Guardian Nitrogen

With the effect of volatilisation and nitrification held in check, more nitrogen is sustained in a useable form for a longer-lasting effect. Your plants are able to take full advantage of the nitrogen you supply, in the stable ammoniacal form. In addition, leaching is held to a minimum.

Guardian provides you with all the benefits of slow-release nitrogen. Long-lasting nitrogen efficiency and performance at a lower cost-per-unit than leading organic, coated and complex chain products.

For more information on how Guardian can help you get the most out of your fertiliser investment, contact us, and we'll help you improve your nitrogen efficiency.

Typical Urea Application

The Nitrogen Cycle

Urea is the most widely-used nitrogen fertiliser in the world. The following steps illustrate the changes undergone by Urea after it enters the nitrogen cycle.

Urea nitrogen fertiliser is introduced into the soil nitrogen cycle as it is surface-applied. From this point forward, Urea is subject to environmental factors that break it apart as it moves through the nitrogen cycle.

Once applied, Urea rapidly undergoes hydrolysis when in the presence of moisture and the enzyme urease. Through this process the urease enzymes in the soil and surrounding plant residue convert nitrogen into two by-products, ammonia and carbon dioxide, both of which are readily lost to the atmosphere.

Loss of Ammonium Nitrogen


On average, 30% of ammonium nitrogen will be lost within days of application through volatilisation unless it is moved into the soil by rainfall or irrigation. Even more can be lost if the Urea is not moved into the soil.

Under normal conditions, %" (2cm) of watering is needed to move Urea into the soil. Until the Urea is moved into soil, watering can also serve to fuel the volatilisation process as moisture combines with urease enzymes, contributing to continued nitrogen loss.

As Urea is moved into the soil, it is moved away from the threat of nitrogen loss through volatilisation. At this point in the soil nitrogen cycle, environmental components again affect the break down of Urea. Once underground, Urea is again broken apart as microbes oxidize the ammonium form of Urea first into nitrites then nitrates. This process is called nitrification.

Leaching of Nitrate

Soil Leaching

After the process of nitrification, plants continue to utilise nitrogen in both the stable ammoniacal (NH4+) and broken-down nitrate form (NO3-).

While the nitrate form of nitrogen is beneficial to plants, under certain circumstances it can also pose a threat to the environment through leaching. Because nitrate nitrogen is an anion, very little is held in the soil profile. The nitrate nitrogen that is not used by plants can be leached into groundwater and lost from the nitrogen cycle.

Another avenue of nitrogen loss can occur when soil becomes saturated through excess rain or irrigation. In this anaerobic soil condition, bacteria will strip oxygen molecules from oxygen-containing compounds such as nitrate (NO3) for respiration. This process is called denitrification.

Nitrogen Utilisation by Plants

Plant Utilisation

Nitrogen is readily utilised by plants once it is moved into the soil. Both ammoniacal nitrogen (NH4+) and the nitrification by-product nitrate (NO3-) are taken in by plants.

Denitriciation by Bacteria


Denitrification by bacteria reduces nitrate into two by-products, nitrogen gas (N2) and nitrous oxide (NO2). Both are readily diffused into the atmosphere and lost from the soil nitrogen cycle.