Fertiliser planning: How did protected urea perform in 2024?
As the permitted period for chemical fertiliser applications is fast approaching, some farmers may be planning their fertiliser use for the year ahead. In this article, Dr. Brian McCarthy and Dr. Áine Murray, Teagasc Moorepark, reflect on the performance of protected urea (urea + NBPT) in 2024.
2024 was a very challenging year in terms of weather and grass growth. Rainfall was 142% higher than average for February, March and April, with sunshine hours also well below average. In contrast, rainfall in May, June and July was only 81% of the average, with huge variation in this figure as the Northwest had above average rainfall, whereas the Midlands, South and East had below average rainfall. Summer temperatures were also below average.
Data from the Moorepark clover research experiment shows that the grass-clover sward receiving 150 kg nitrogen (N)/ha, grass production for 2024 was 11.2 t dry matter (DM)/ha, a 19% reduction compared to the 5-year average (13.8 t DM/ha). In contrast, the grass-clover sward receiving 150 kg N/ha in the Clonakilty clover research experiment produced 14.5 t DM/ha, a 1% increase on the 5-year average (14.3 t DM/ha). Both research experiments have been using urea + NBPT for all of their straight N requirements for the last number of years. Nationally, grass production was down by 1.1 t DM/ha to 11.3 t DM/ha in 2024, with large variations across the country. Table 1 highlights some of the variation observed between locations, regardless of the fertiliser type used.
Table 1. Grass production in 2024 compared to 5-year average from 4 farms across the country
|
2024 grass production YTD (t DM/ha) |
5-year average grass production (t DM/ha) |
|
|---|---|---|
| Tipperary - 100% urea + NBPT | 11.4 | 11.3 |
| Cavan - 100% urea + NBPT | 13.7 | 13.3 |
| Kilkenny - 100% CAN | 8.4 | 12.0 |
| Cork - 100% CAN | 11.7 | 14.0 |
Data from a plot study undertaken in Moorepark and Clonakilty in 2024 showed no difference between CAN and urea + NBPT, under a grazing scenario, in terms of pre-grazing yield (1,603 vs. 1,553 kg DM/ha for CAN and urea + NBPT, respectively; Table 2 and Figure 1) or total grass DM production (11.4 vs. 11.3 t DM/ha for CAN and urea + NBPT, respectively; Table 2).
Table 2. Effect of fertiliser type and rate on pre-grazing yield and annual grass production in 2024 (average of Moorepark and Clonakilty)
| Fertiliser type | 120 kg N/ha | 200 kg N/ha | ||
|---|---|---|---|---|
| N rate (kg N ha-1) | CAN | Urea + NBPT | CAN | Urea + NBPT |
| Pre-grazing yield (kg DM/ha) | 1,483 | 1,449 | 1,728 | 1,661 |
| Cumulative yield (kg DM/ha) | 10,560 | 10,702 | 12,221 | 11,883 |
Figure 1: Effect of fertiliser type on pre-grazing yield by rotation in 2024 (average of Moorepark and Clonakilty)
In 2024 in Moorepark, soil N mineralisation was reduced by 30 kg/ha (16%) compared to previous years, due to the poor weather. This effect was exacerbated in grass-clover swards as biological N fixation was also reduced by 50 kg/ha (approximately 50%) in 2024.
To summarise, 2024 was a very difficult year for grass growth in many areas of the country. Although there were issues with protected urea in 2024 in terms of difficulties in spreading causing striping etc., based on the ongoing research with side by side comparisons, there was no difference between CAN and urea + NBPT in terms of grass growth in 2024, similar to previous years.
The above was adapted for use on Teagasc Daily from the article titled: ‘How protected urea performed for grass growth in 2024’, which was first published in the Irish Farmers Journal Signpost Programme focus.
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