About Efficiency Enhancers
Fertilisers Efficiency Enhancers
The use of nitrogen is essential for agricultural production but only about 50% of nitrogen applied through nitrogen-containing fertilisers is absorbed by crops.
Nitrogen fertilisers can contain nitrogen in various forms such as urea, ammonium (NH₄⁺) or nitrate (NO₃⁻) and their combinations, as well as organic nitrogen. Urea nitrogen is not readily plant available. The naturally occurring urease enzyme transforms urea-nitrogen into ammonium (NH₄), which can be taken up in much higher amounts by crops. This process, called ”hydrolysis”, is catalysed by specific soil enzymes (urease enzymes), and occurs when urea is applied to the soil surface producing regular losses of 10-30% of ammonia to the atmosphere, through a process known as ”ammonia volatilisation”.
Ammonia losses negatively affect crop yields and/or its quality. When in contact with particulate matter, ammonia forms smog causing health problems for humans. When ammonia redeposits on soil or in water, it can be the cause of acidification and eutrophication, which have a heavy negative impact on biodiversity.
Urease inhibitors (UIs)
Urease inhibitors (UIs) can be used to slow down the hydrolysis of urea thereby reducing ammonia (NH3) emissions by 70% (Bittman et al. 2014). This results into more nitrogen remaining available for growing crops and a reduction of the negative impact that ammonia emissions can have on the environment.
Urease inhibitors can also reduce nitrous oxide (N₂O) emissions.
Nitrification inhibitors (NIs)
While nitrogen in its ammonium (NH₄⁺) form is retained by the soil and made available to crops, naturally occurring soil bacteria convert it into nitrate (NO3-) releasing nitrous oxide (N₂O) in the atmosphere. The conversion of ammonium into nitrate is called nitrification. Nitrous oxide is a very potent greenhouse gas (273 x CO₂) with an atmospheric lifetime of over 100 years.
Nitrate can be reduced to nitrous oxide (N₂O) and nitrogen gas (N₂) through denitrification. N₂O is then released in the atmosphere leading to ozone layer depletion. While nitrate can be easily taken up by crops, it is very mobile and can easily leach into ground and surface water, leading to eutrophication (the formation of toxic algal blooms) and a loss of biodiversity. One solution to minimise nitrogen losses through nitrification and denitrification is the use of nitrification inhibitors (NIs), which specifically inhibit the activity of soil microorganisms responsible for converting ammonium to nitrate. As a consequence of the use of nitrification inhibitors, nitrous oxide emissions and nitrate leaching are reduced. This results in ammonium being available to crops for a longer period and in a form that best meets their needs, which has an overall positive impact not only on farmers but also on the environment.