Is protected urea a runner in 2025?

After receiving unprecedented negative press in 2024, it remains to be seen how much protected urea will be used in 2025. Teagasc have come out strong to say that reductions in grass growth have come about as a result of the poor growing conditions in 2024, not because protected urea doesn’t work as well as CAN.

On the grass and clover trials in Moorepark with 150kg N/ha applied, grass growth was 11.5t DM/ha for 2024, back 17% on the five year average.

To show the regional variation, the same treatment in Clonakilty grew 15t DM/ha, up 5% on the five year average.

Writing in Today’s Farm, Teagasc researcher Aine Murray says both trials have been using protected urea for the last number of years.

In grazing plots at Moorepark and Clonakilty, protected urea was compared with CAN and no significant difference in grass growth was observed, with the average of the CAN plots growing 11.4t DM/ha and the protected urea plots growing 11.3t DM/ha.

Furthermore, in cutting plots at Johnstown Castle, no significant difference was found between different types of nitrogen fertiliser applied on these plots in 2024.

Despite these assurances, many farmers are questioning whether or not they will purchase protected urea in 2025.

One issue which everyone accepts is the spreadability of urea-based fertilisers.

This is proving to be a big issue and led to very obvious striping in many fields last year, particularly where compound fertilisers containing protected urea were used.

Urea is a more difficult product to spread than CAN anyway.

This is because is has a lower bulk density and a lower hardness score. Bulk density is the weight per volume and this is lower in urea.

For example, a big bag of urea weighs 375kg whereas a big bag of CAN weighs 500kg.

Speaking at Dairy Day last November, Liam Dunphy, the managing director of Goulding fertiliser company used the analogy of the golf ball and the ping pong ball – both look the same but their bulk density is very different and you can throw a golf ball much further.

So because urea has a lower bulk density, it is harder to get a wide and even application when spreading.

If spreading a protected urea based compound fertiliser such as 29:0:14+S, the product may be applied evenly across the area to be covered, but the issue could be that the urea is concentrated near the spreader and the potash and sulphur travelled further than the urea granules, having a higher bulk density and larger granule thus leading to striping.

The second issue is hardness and this is tested by applying force to a granule of fertiliser.

At what point, or level of force the granule breaks determines the hardness score. Teagasc say that fertiliser should have a hardness score greater than 5kg and a minimum of 3kg. Typically, good quality CAN will have a hardness score of 7kg to 8kg and good quality urea will have a hardness score of 3kg or so.

Liam Dunphy explained that the longer urea is exposed to the atmosphere, the lower the hardness will be as it attracts moisture.

He said that in the past, urea was bagged as quickly as possible once it arrived in the warehouse to limit its exposure to air.

He went on to say that urea is now left in warehouses for longer as it needs to be coated with the protected urea before it can be bagged and so it soaks up more moisture from the air.

Plus, he said the liquid coating to give it its protection reduces the hardness also.

It’s a fact that many farmers tested protected urea in 2024 with a hardness score of 1kg or 2kg, well below the minimum recommendations.

The issue with low hardness is that the product will break easier once it hits the vanes on the fertiliser spreader, meaning it won’t travel as far, which again leads to striping.

Also speaking at the Dairy Day panel was David Wall from Teagasc and he said that wagtail fertiliser spreaders have a less impactful way of spreading fertiliser compared to disc spreaders and so softer granules are less of a problem.

But as the vast majority of fertiliser spreaders are now disc spreaders, the hardness of the product is a big issue.

The stock answer to a lot of issues around protected urea last summer was to blame incorrect calibration of the fertiliser spreaders.

I know of farmers who engaged with experts last summer and spent hours trying to get fertiliser spreaders calibrated correctly using tray tests, but the issues around hardness and density made that almost impossible.

What to expect this year

The challenge for farmers is to come up with a fertiliser plan that will be effective while also reducing agriculture’s greenhouse gas footprint.

The messages from the Dairy Day session, which included dairy farmer Tom Downey from Golden in Co Tipperary, was to focus on straight protected urea first and foremost.

This is protected urea without any other nutrient included such as sulphur or potash and it was felt that this would have been handled less often and should spread easier as it would have a consistent bulk density.

Tom said that he was going to soil sample again this winter and if he had a P allowance he was going to apply some 18:6:12, which has a low carbon footprint.

This would provide some P and K and there is also the option to include sulphur in this.

On sulphur, he said he plans to use ASN fertiliser which is 26% nitrogen and 14% sulphur although Liam Dunphy cautioned that this product may be in short supply in 2025.

Nitrogen rates for 2025

For 2025, the maximum amount of nitrogen that can be applied on higher stocked farms is 213kg N/ha or 171 units/acre.

In my view, farmers that have this allowance should be using it, especially those that have good perennial ryegrass swards that are responsive to nitrogen.

As we learned in 2024, clover is volatile. According to Teagasc, the amount of N fixed by clover was back 50kg N/ha or 50% in Moorepark in 2024. The amount of N mineralised by soil microbes was back by 30kg N/ha or 16%.

So while 2024 was a difficult year for clover, there is no reason to suggest that 2025 will be the same and farmers should continue to farm for high clover swards as it brings about many benefits in terms of fixing nitrogen and improving animal performance.

However, the nitrogen tap should only be turned off when the clover content is sufficient to deliver the chemical nitrogen foregone.

The lesson from 2024 is that clover is not as dependable as some thought.

Table 1 highlights the Teagasc recommendations for nitrogen fertiliser at a maximum rate of 212kg N/ha.

Farmers at lower stocking rates will have lower allowances.

Slurry and soiled water are in addition to these monthly rates.

Comment

The push towards protected urea is logical from the point of view that it reduces Ireland’s greenhouse gas emissions and the science says it doesn’t have any impact on grass growth.

However, it’s important to note that most of these head-to-head trials are carried out in plots where the fertiliser is applied by a hand-spreader, therefore the spreading issues experienced on many, but not all, commercial farms aren’t appearing.

Teagasc will need to broaden the scope of protected urea research on to commercial farms for comparisons with different fertiliser types, spreaders, soil and weather conditions to rebuild confidence in protected urea. Other areas are also worth exploring such as liquid fertiliser, true compounds and new blends.

In short