Incorporating white clover and protected urea into intensive grazing systems
The Clonakilty Agricultural College experiment from 2019-2021 investigated how reducing N fertiliser application levels on grass-only and grass-clover swards effected grass and milk production. Brian McCarthy, Research Officer and Áine Murray, Walsh Scholar, Teagasc Moorepark have more details
Photo above: Grazing plots at the Clonakilty Agricultural College protected N experiment
The Clonakilty Agricultural College experiment from 2019-2021 entitled “The effect of sward type (grass-only vs. grass-clover) and nitrogen (N) fertiliser level (150 vs. 250 kg N/ha) on the productivity of spring milk production systems” investigated how reducing N fertiliser application levels on grass-only and grass-clover swards effected grass and milk production.
Perennial ryegrass-white clover swards continue to show benefits in terms of milk and milk solids production. Over the three years, grass-only swards produced, on average, 5,549 kg milk and 468 kg milk solids (kg fat + protein) per cow/year, in comparison with the grass-clover swards that produced 5,859 kg milk and 499 kg milk solids per cow/year. This milk response was evident even at lower sward white clover contents (17%) than previous experiments compared to grass-only swards. Interestingly, N fertiliser rate did not have a significant effect on milk production or composition over the three years. In terms of grass production, sward white clover content was not high enough on the grass-clover-150 treatment to fully offset the 100 kg reduction in N compared to the grass-only-250 treatment (14.6 vs. 15.2 t DM/ha). Grass production, however, was higher for the grass-clover-150 treatment compared to the grass-only-150 treatment (13.8 t DM/ha). The results from this experiment show that white clover will continue to play an important role in facilitating reductions in N use and improving nitrogen use efficiency on dairy farms.
Along with this system experiment a grazing plot investigation was carried out from 2019-2021 comparing the efficacy of CAN, Urea and NBPT-Urea at both 150 kg N/ha and 250 kg N/ha at four site locations, Clonakilty, Moorepark, Athenry and Ballyhaise. Athenry and Ballyhaise were added in 2020. There was no evidence of difference in efficacy between the CAN and NBPT-Urea, as both supported similar herbage production and pre-grazing yields. There was slightly higher herbage production for CAN and NBPT-Urea than ordinary urea.
Authors: Brian McCarthy, Research Officer and Áine Murray, Walsh Scholar, Teagasc Animal and Grassland Research and Innovation Centre, Moorepark, Fermoy, Cork.
In this video clip, ACP Agronomist Bridget Lynch & Moorepark AGRIP Researcher Brian McCarthy give an update on research to reduce N fertiliser use with white clover.
Further information
The Agricultural Catchments Programme (ACP) is running a week of social media releases showcasing some of its activities from Monday 21 February to Friday 25 February. The week’s theme is “Working Together for Water Quality”. More details of what is on can be found at www.teagasc.ie/ACPweek22