The use of white clover offers many benefits to farmers

The use of white clover in grassland offers many benefits to Irish farmers, including to replace fertiliser nitrogen (N), which will substantially lower greenhouse gas (GHG) and ammonia emissions from pasture-based production.

The benefits of white clover tend to occur from May onwards, as sward white clover content increases.

The main benefits of white clover inclusion in grass swards are:

• Increased herbage quality compared to grass-only swards in the summer months;
• Increased dry matter (DM) intake in summer and autumn;
• Higher milk production and liveweight gain;
• Nitrogen fixation – white clover fixes N from the atmosphere making it available for plant growth;
• Lower requirement for N fertiliser application in summer.

Latest dairy research

Teagasc has been carrying out research for eight years (2013-2020) at Moorepark, comparing the standard grass-only grazing system receiving 250kg fertiliser N/ha/year with a grass-white clover system receiving 150kg N/ha/year. Both grazing systems were stocked at 2.74 cows/ha.

Similarly, at Clonakilty Agricultural College, a grass-only system receiving 250kg N/ha/year was compared with a grass-white clover system also receiving 250kg N/ha/year, stocked at 2.75 cows/ha over four years (2014-2017).

The results of these trials are outlined the table below.

Grazing management for white clover swards

Best practice grazing management is similar for grass-white clover swards and grass-only swards.

Flexibility and willingness to adapt to the conditions are important when managing grass-white clover swards.

Good grazing management is also important for increased persistence and production of white clover in grazed swards.

Spring:

• Target early spring grazing – this benefits white clover growth;
• Avoid poaching/damaging swards – poaching reduces white clover content in the sward;
• Be flexible – use on/off grazing, graze wetter paddocks in drier weather;
• Target post-grazing sward height of 3.5cm.

Mid-season (April to July):

• Maintain pre-grazing herbage mass between 1,300 and 1,600kg DM/ha (8 to 10 cm);
• Target post-grazing sward height of 4.0cm;
• Chemical N fertiliser may be reduced on swards with good white clover content (≥ 25%).

Autumn:

• Build grass on the farm from early to mid-August by extending rotation length;
• Close the farm in rotation from early October;
• Target post-grazing sward height of 3.5 to 4.0cm on the final rotation;
• Avoid poaching/damaging swards;
• Be flexible – use on/off grazing, graze wetter paddocks in drier weather;
• Chemical N fertiliser may be reduced in August on swards with good white clover content (≥ 25%).

An average annual sward white clover content of approx. 20 –25% is desirable for animal and sward production benefits.

Sward white clover content increases through the spring, into summer and generally peaks in August/September.

Good grazing management is key to maintaining sward white clover content.