Time to Reassess Fertiliser Type
By Enda O’Hart ,
Drystock Adviser, Teagasc Castlerea.
As we are now in an era where sustainability is key in all farming systems, farmers are been asked to re-examine the type of chemical nitrogen fertiliser they use. Nationally the government have committed to reducing ammonia and Green House Gas (GHG) emissions. Currently agriculture accounts for 33% of our national GHG emissions, and 98% of our national ammonia emissions. The use of protected urea nitrogen fertiliser is the largest single avenue currently open to Irish agriculture to meet the commitment to reduce GHG and ammonia emissions.
Currently urea and CAN (Calcium Ammonium Nitrate) are the 2 main types of straight Nitrogen fertiliser products used on Irish farms. The main problem with the use of regular urea is that as it breaks down large losses of ammonia gas can occur. The use of CAN leads to significant production of Nitrous Oxide N2O which is a very potent greenhouse gas. Replacing CAN with protected urea will reduce Nitrous Oxide emissions by up to 71%. Replacing urea and CAN with protected urea will lead to reduced emissions of both ammonia and nitrous oxide which represent financial gains for the farmer and a gain for the environment in terms of air quality, water quality and climate change.
Protected urea is urea which is treated with an active ingredient called a urease inhibitor. Urease is a naturally occurring enzyme which speeds up the conversion of urea to ammonium. It is during this process that ammonia gas can be lost to the atmosphere. The urease inhibitor slows the rate at which urea is converted to ammonium and in doing so ammonia losses are reduced to low levels. There are 3 different urease inhibitors used to manufacture protected urea NBPT, 2-NPT and NBPT+NPPT, so ensure any product purchased contains one of the above inhibitors
One of the main benefits of protected urea is that it can be used throughout the growing season to replace urea and CAN. There are no reductions in grass yields when using protected urea versus urea or CAN, regardless of what time of the growing season it is used. Trials have also shown that the nitrogen recovery efficiency of protected urea and CAN are consistently the same.
In terms of cost, protected urea is approximately €30 - €40 more expensive than urea per tonne, but on a per unit basis it is about 10% cheaper per unit than CAN and 10% more expensive per unit than urea. Protected urea should only be used to replace slots in a fertiliser plan where straight nitrogen applications of urea or CAN are planned. It is not intended to replace compound fertiliser applications for example 10:10:20, 18:6:12 etc...
With all this information in hand farmers should not be afraid to start replacing urea and CAN with protected urea. In doing so, this change will yield real dividends in terms of improving our environment and making agriculture more sustainable.
Teagasc provides a Local Advisory and Education service to farmers. They have offices based in Longford Town (Tel: 043 3341021), Roscommon Town (Tel: 090 6626166) and Castlerea (Tel: 094 9620160). You can find us on Facebook @Teagascroscommonlongford and twitter @teagascRNLD