30 April 2025

Nitrogen application strategies for grass-white clover swards

With April turning to May, farmers may be considering reducing chemical nitrogen applications to grass-white clover swards. Dr. Áine Murray of the Teagasc Grassland Department shares some key tips to ensure this is done in the most effective way to prevent a drop in total dry matter production.

When reducing nitrogen fertiliser to grass-white clover swards, it’s crucial to ensure there is adequate clover content in the sward, ideally over 20%, to prevent a decrease in total dry matter production. This typically happens from May onwards, due to rising temperatures and growth rates, leading to an increase in clover content. Prior to this and during the spring, clover content tends to be lower, so nitrogen application should follow a similar approach to that used for a grass-only sward.

In order to assess the clover content, individual paddocks should be walked and evaluated using the Teagasc Clover Content Scorecard, with the findings then recorded for each individual paddock on PastureBase Ireland.

Once the clover content has been assessed, nitrogen strategy should be chosen based on Teagasc’s guidelines, tailored to the clover content in each paddock, and outlined in table 1 below. This strategy can then be incorporated into your nitrogen plan in the PastureBase Ireland app to reduce your chemical N use in grass-clover swards.

Table 1: Nitrogen strategy based on clover percentage

• *Chemical N fertiliser can be increased to 230kg N/ha, in paddocks with no clover, as long as whole farm N does not exceed 212kg N/ha
• Soiled water used whenever zero chemical N application
• +25kg organic N applied

Dr. Áine Murray shares more insights on effective fertiliser programmes for grass-white clover swards in the below video:

More from Teagasc Daily: Dr. Michael Egan’s tips on establishing grass/white clover swards