Nitrogen losses
Nitrogen losses from ammonia, nitrate and nitrous oxide all occur at different stages of the nitrogen cycle. All nitrogen fertilisers are subject to some degree of loss, no matter the source, and innovative technologies can help minimise these losses.
Urease inhibitors
Nitrification inhibitors
Urea/UAN application
Slurry or mineral ammonium application
Average ammonia losses
Average nitrous oxide losses
~ 20%
~ 1%
- 98%
- 50%
Hydrolysis
Nitrification
Nitrate Plant available
Nitrite
Ammonium
Urea
Urease Enzymes
Nitrosomonas
Nitrobacter
Plant available (limited)
Plant available
- 35%
~ 25%
Limus ®
Vizura ®
Average nitrate losses
How do nitrogen losses occur? Hydrolysis: Urea fertiliser has limited availability to plants. It must frst go through a process called hydrolysis, where urease enzymes convert it to plant available ammonium. During this process, some of the ammonium can be lost as ammonia through volatilisation. Ammonia: Ammonia losses from urea based fertilisers can be up to 80% of the total applied nitrogen, depending on the urea fertiliser type, climate and soil pH value. In the UK, the DEFRA funded NT26 project concluded that around 20% of applied nitrogen from granular urea is lost as ammonia. For UAN these average losses are around 14%.
Nitrification: Ammonium, either from hydrolysis or following application of ammonium nitrate or slurry, is plant available and can be taken up and metabolised easier than nitrate. However, ammonium is rapidly converted into nitrate during a process called nitrifcation. Nitrosomonas bacteria in the soil change the ammonium to nitrite, which then gets converted into nitrate by nitrobacter. Nitrate: Nitrate is negatively charged so no longer binds to the soil. Water can then transport it down the soil profle out of reach of the roots. Typically, nitrate leaching is worse in the winter when the soils are at water holding capacity. On light soils, leaching can occur in the spring following a heavy rainfall event.
Nitrous oxide: Nitrous oxide can also be given off during this process. Although typically only 1% of applied nitrogen is converted to nitrous oxide, it is a powerful greenhouse gas, 298 times more potent than carbon dioxide. Therefore contributes signifcantly to agricultural greenhouse gas emissions. How can technologies reduce nitrogen losses? Urease inhibitors: Urease inhibitors slow down the hydrolysis process, minimising losses from ammonia. Limus ® reduces ammonia losses by up to 98%, making more nitrogen available to crops.
Nitrification inhibitors: Nitrifcation inhibitors inhibit the Nitrosomonas bacteria, preventing the conversion of ammonium to nitrite. The use of a nitrifcation inhibitor like Vizura ® , reduces nitrous oxide emissions by around 50% and leaching by around 35%.
Only 50% of applied nitrogen is taken up by crops.
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