At the start of each fertiliser season, there is always much debate on the most cost effective source of nitrogen (CAN 27% N or urea 46% N). This debate has become much more active, with the introduction of a new option in the form of protected urea. The Government’s Climate Action Plan aims to replace 50% of the straight CAN used on Irish grasslands with protected urea. This gives farmers a cost effective option to reduce GHG (Greenhouse Gas) emissions, without reducing production.

So what is protected urea, and what do Teagasc mean when they use this term?

Protected urea is urea fertiliser treated with a urease inhibitor, making urea safe from ammonia-N volatilisation loss, which is the problem with ordinary urea. At present, only three urease inhibitors are registered under the National or EU fertiliser regulations.

What products are protected with the urease inhibitors above?

Teagasc will keep a list updated on the soil fertility website under the protected urea tab.

How will a farmer be sure the fertiliser he is buying is urea protected with a urease inhibitor?

The bag or label should state ‘urea with urease inhibitor’ and the type of inhibitor used.

How can I be sure the urease inhibitor is on the fertiliser at the right rate to protect it?

The Department of Agriculture, Food and the Marine will be carrying out market surveillance to ensure that the use of urease inhibitors on fertiliser sold to farmers meets with regulatory requirements.

What does the research say about protected urea yield performance?

Teagasc research conducted around the country has shown that urea protected with a urease inhibitor consistently gives the same yield as CAN (Figure 1). At times of the year when CAN yields were up, protected urea yields were also up. However, if growth conditions were unfavourable due to weather, the yields of both fertilisers were reduced.

What does the research say about GHG emissions?

In trials conducted at six sites around the country, protected urea reduced emissions compared to CAN. As a result, if farmers shift to using protected urea in place of CAN, they can reduce emissions on-farm and can get credit for these GHG emission savings.

What does the research say about ammonia?

The research shows that the registered urease inhibitors (Table 1.) make urea safe from ammonia volatilisation, meaning more N is retained to grow grass compared to ordinary urea.

When can I use protected urea?

You can use it throughout the growing season in the straight N or N+S slots in your fertiliser programme. Use standard compound fertilisers to apply P and K e.g. 18:6:12.

Apply 50% of grassland P requirements in March/April (first/second split), time and apply the remaining 50% in May/June. Applying a 50:50 split of P will ensure early season P for grass yield and mid-season P in grazed grass.

Will protected urea cost me more?

Protected urea is currently circa 10% cheaper per unit of N than CAN and circa10% more expensive than urea.

Is urea protected with a urease inhibitor safe to handle?

Like all other fertilisers protected urea should be handled with care. However, the safety data sheets show that protected urea is safer to handle than CAN.

In conclusion

Protected urea is safe to use throughout the growing season in the straight N slots in a fertiliser programme, giving reliable yield and reduced emissions in a cost effective way.