NBPT Urea (Protected Urea) on late-sown barley - the opportunities

Through advancements in technology, Teagasc Signpost Programme Tillage Advisor, John Mahon explains how farmers can use NBPT urea products to not only save on input costs but to also reduce their carbon footprint when growing barley.

The use of urea as a nitrogen (N) source on spring crops – particularly if sown late – was not recommended prior to now, as the risk of volatilisation and release of ammonia nitrogen to the atmosphere was greatly increased with the warmer air temperatures associated with applications in late April and May.

Now, however, with technological advancement, it is possible to avail of the lower cost per unit of N chemical fertiliser urea without suffering the lower productivity associated with these losses (the EPA estimates that ammonia loss from urea is 15.5% on average).

A fertiliser coating (NBPT) at the point of manufacture now ensures that the applied nitrogen source remains stable under warmer conditions and maintains a more stable release of N over time, hence the name ‘protected urea’. This form of fertiliser is available from all of the main chemical fertiliser suppliers in Ireland and can be purchased as normal from any local stockist.

The cost savings, while not the same as straight urea due to the extra cost associated with the addition of the protectant coating, are comparatively lower (normally 16-20%) than Calcium Ammonium Nitrate (CAN), which is usually the alternative nitrogen source used on late-sown crops in late April and May.

Table 1: Comparative cost €/kg N of urea, protected urea and CAN (27% N)

But does it perform well in the field on spring barley?

Teagasc research trial work over a three year period on spring barley in Co. Wexford would suggest that protected urea performs better than both straight urea and CAN.

The trial highlighted a 78% reduction in ammonia emissions compared to straight urea (Figure 1). Average nitrogen uptake was higher with the protected urea compared to both straight urea and CAN (Figure 2), and when comparing yields the protected urea performed better than both urea and CAN (Figure 3).

This suggests the N use efficiency is greater when using protected urea, which may allow for slightly lower spread rates on farm to get the same result, further reducing costs on farm. Further research is required to collaborate these findings on various soil types with different sowing dates.

Figure 1: Average cumulative ammonia emissions over 3 years – urea vs protected urea

Figure 2: Average Nitrogen uptake over 3 years – CAN/Urea/Protected Urea

Figure 3: Average grain yield over 3 years – CAN/Urea/Protected Urea

Environmental benefits

From an environmental point of view, approximately 70% of greenhouse gas emissions associated with tillage farms are directly related to the use of nitrogen. Anything which can lead to less N being applied and/or greater N use efficiency from the applied N source will automatically lower the carbon footprint on the farm.

The trail work also highlighted protected urea had significantly lower GHG nitrous oxide emissions compared to both straight urea and CAN (Figure 4), in addition to the reduction in ammonia losses to the atmosphere.

Figure 4: Average Nitrous Oxide emissions over 3 years – CAN/Urea/Protected Urea

Summary

The opportunity to replace straight urea or CAN with NBPT Urea (Protected Urea) as the main N source on late-sown spring barley this season offers a farmer lower input cost per hectare with similar yield expectations, and also lower the farm’s GHG emissions.

It’s a win/win for both farm profitability and the environment, leading to a more sustainable future.

Additional information

In the below video, Dermot Forristal and Brendan Burke, from Teagasc Oak Park, explain how to set up a fertiliser spreader correctly so that NBPT Urea (Protected Urea) can be accurately spread on tillage crops.

The Teagasc Signpost Programme has also prepared a useful inforgraphic to follow when spreading urea, see below:

Click here for detailed information on calibrating your fertiliser spreader.

More information on the Teagasc Signpost Programme is available here.