Agronomy Advice
March 08, 2023

White Clover reduces Nitrogen Application Requirements

For six years Moorpark in Ireland have been conducting trials exploring the impact growing white clover in paddocks along with perennial ryegrass has on nitrogen requirements.

tractor on a open field
tractor on a open field

The premise is that by introducing white clover should reduce the amount of nitrogen needed to maximise productivity of that paddock.

Benefits of growing white clover in paddocks

Up until May of each year nitrogen applications of 250 kg/ha N were made on two leys: one growing perennial ryegrass alone and the other adding white clover. After May, the application on the ley which contained white clover was reduced to 150 kg/ha N.

The results over the six years have been consistent:

  • Herbage production remains the same (14.5t DM/ha) on clover leys receiving less N
  • Milk solids have increased from cows grazing on clover leys (+33 kg/cow).
  • Nitrogen Use Efficiency has improved by 19% on the clover at 150 kg/ha N treatment.

How to maintain good clover content in paddocks

The benefits are being seen where clover contents were on average 20-25% throughout the year. But maintaining a good coverage of clover requires good grassland management.

Clover has a higher minimum soil temperature requirement than grass so grass grows quicker at the beginning of the year. To ensure that it doesn’t completely out-compete the clover, it’s essential that the grass is sufficiently grazed at this time.

Applying nitrogen will benefit white clover at the start of the season as it will use the applied N for growth at a point when it’s not fixing its own nitrogen. This is why nitrogen rates are not dropped until May, to provide clover with that initial growth spurt before it’s able to support itself.