Management of red and white clover in Irish beef grass-based systems

Michael Egan Peter Doyle

There has been a significant renewed interest in the role of legumes – both white and red clover – on Irish grassland farms in recent years, with seed sales having increased to 353 t and 131 t for white and red clover, respectively, equating to a 40% increase in 2025 from 2020. The main benefits of including clovers in grass-based production systems are:

• Nitrogen (N) fixation. White clover fixes N from the atmosphere making it available for plant growth. Depending on N fertiliser application rate and sward clover content, white clover can fix up to 100 kg N/hectare (ha) per year and red clover up to 200 kg N/ha per year.
• Animal performance advantage. Compared to grass-only swards, grass-white clover swards have:
  • Increased crude protein and digestibility
  • Increased beef cattle performance – cattle grazing grass-white clover swards or consuming red clover-grass silage have greater average daily gains up to 0.1 kg/day.
  • Increased dry matter (DM) intake by up to 12% in white clover grazing systems.

The benefits of white clover tend to occur from late April/early May onwards as sward clover content increases. However, the ongoing challenge is to ensure that sufficient levels of clover (20% average sward white clover content across the grazing season and greater than 50% average sward red clover content for grass-red clover silage harvests in a multi-cut system) are achieved and maintained on farm to realise these production and economic benefits when incorporating legumes into grass-based production systems.

White clover: management in grazing swards

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-clover swards. Good grazing management is also important for increased persistency and production of white clover in grazed swards. Grazing management guidelines for spring, mid-season and autumn are as follows.

Spring

• Target early-spring grazing – this benefits white clover growth.
• Avoid poaching/damaging swards – poaching reduces white clover content.
• Be flexible – use on/off grazing, graze wetter paddocks in drier weather, etc.
• Target 3.5-4.0 cm post-grazing sward height to allow light to the base of the sward.

Mid-season (April to July)

• Maintain pre-grazing herbage mass between 1,300 and 1,600 kg DM/ha (8 to 10 cm).
• Target 4 cm post-grazing sward height.
• Chemical N fertiliser may be reduced in the mid-season on swards with >20% white clover content.

Autumn

• Build grass on the farm from early to mid-August – extend rotation length.
• Close the farm in rotation from early October.
• Target post-grazing sward height of 4.0 cm on the final rotation.
• Close paddocks with a high sward white clover content (i.e. > 30%) towards the end of the final rotation (end October/early November).
• Avoid poaching swards.
• Be flexible – use on/off grazing, graze wetter paddocks in drier weather, etc.

An average annual sward white clover content of approximately 20% is required to achieve animal and sward production benefits. In general, sward white clover content increases through the spring (<10%), into summer (15-20%) and generally peaks in August/September (>35%). Good grazing residual management is key to increasing and maintaining sward clover content over and across years.

Soil fertility is another key aspect in ensuring that white clover will establish and persist. A soil pH of 6.5 is essential for white clover development and persistency. Low soil pH reduces soil nutrient availability for plant growth and the formation of nodules (that contain Rhizobium bacteria), which are required for biological N fixation (BNF). White clover requires a minimum of soil Index 3 for both phosphorus (P) (5.1 – 8 mg/l) and potassium (K) (101 – 150 mg/l). Soil P and K availability are also important for BNF, which is reduced when there is a P and/or K deficiency.

Early N fertiliser application is important to encourage growth and development of white clover and perennial ryegrass. As BNF is very limited in early-spring, N fertiliser should be applied to grass-white clover swards at similar rates to those used in grass-only swards. Subsequently, in the summer, when sward clover content reaches 20% and BNF increases, N fertiliser application can be reduced. Some N fertiliser may be required in autumn to increase herbage supply. Suggested N application strategies for grass-clover swards with a range of sward clover contents are shown in Table 1.

Table 1. Nitrogen fertiliser application strategy for a drystock farm (stocking rate 170 kg organic N/ha) based on sward white clover contents in April

¹5% clover content in April = 10% average annual sward clover content
²10% clover content in April = 15% average annual sward clover content

Red clover

Red clover is a deep tap rooting, N fixing legume that is primarily used for silage production. It offers high yields of up to 15 t DM/ha in a 3-cut system and can fix between 150-200 kg N/ha per year. Red clover, however, has a different growth habit to that of white clover and requires different management to optimise its performance. Consequently, it can be more complicated to manage than conventional grass-only silage swards. The crown of the red clover plant acts as the growing point and is located above ground level. The stem grows upwards from the crown. The crown of the plant should be protected from compaction, poaching, overgrazing or cutting too low to maintain the proportion of red clover in the sward. As such, red clover requires different management to perennial ryegrass or white clover systems and should only be used in a silage production system (ideally a 3-cut system). It is not suited to intensive grazing.

Establishing a grass-red clover sward

• Red clover performs best on well-drained, fertile soils.
• Spring/early summer reseed provides best results – April, May, June.
• Spray off the old pasture with glyphosate.
• Prepare a fine, firm seedbed.
• Target soil pH 6.3 – 7.0 and Index 3 for P and K.
• Sowing rates: Grass, 22 kg/ha (9 kg/acre) and red clover, 10 kg/ha (4 kg/acre).
• Use the UK Recommended List for cultivar selection.
• White clover seed can also be an option to incorporate into the seed mix.
• Use a clover-safe post-emergence herbicide during suitable weather conditions.

Managing red clover in silage systems

• Multi-cut system – three to four harvests per year.
• Six-to-eight week cutting intervals – optimises silage quality.
• First-cut should be targeted in early-to-mid May – increases clover content in subsequent defoliations.
• Avoid excess chemical N fertiliser applications – <35 kg N/ha (28 units/acre) for first-cut when red clover content is often low (~15 %), and zero N fertiliser application for second- (~50% red clover) and third- and fourth- (~80% red clover) cuts as red clover content and BNF increases.
• Red clover silage has a high P and K requirement (ensure adherence to the farm’s chemical P allowance):
  • The majority of the nutrient requirements for grass-red clover silage swards can be met from slurry – 1000-gallons slurry/acre equates to 9-5-32 units/acre or 4.5-2.5-16 kg/ha, for N, P and K, respectively.

Table 2. Recommended fertiliser application plan for a grass-red clover silage system

• Ensure adequate wilting time (target ≈ 30% DM) – but avoid leaf shatter when raking in.
• It can be difficult to get a good wilt and preservation in autumn (target 3^rd cut date ≈ end of August, and 4^th early October if applicable).
• Avoid soil compaction during wet weather – may cause crown damage, and plant loss.
• Target a cutting height of 5 cm.
• Avoid frequent grazing of grass-red clover swards – however, grazing may be required following the final harvest in late autumn to avoid carrying a heavy herbage cover over the winter. It is essential to follow the relevant bloat precautions when grazing and avoid grazing too severe (< 6 cm) to prevent crown damage.
• Red clover contains up to 1% oestrogenic compounds, resulting in reduced ewe fertility.
  • Avoid grazing red clover sward with ewes 6 weeks before and after mating.
• Red clover is susceptible to several pests and diseases although incidences in Ireland are rare.
  • Stem eelworm is the major pest of red clover.
  • Clover rot (Sclerotinia) is the most serious disease affecting red clover.
  • A 5-year break between red clover crops is recommended to combat pests and diseases.

Conclusions

The benefits for Irish beef farmers of including white clover in grazing swards and red clover in silage swards include reducing fertiliser inputs, increasing animal production, and lowering overall greenhouse gas emissions. However, successful incorporation and maintenance of target clover contents in swards depends on careful management, particularly around grazing (white clover) and cutting (red clover) management, soil fertility and fertiliser management. Farms that adapt their management practices can achieve high clover contents in swards and also long-term clover persistency, thus reducing the reliance on chemical N fertiliser inputs.

Compiled and edited by Mark McGee and Paul Crosson, Teagasc, Grange Animal & Grassland Research and Innovation Centre, and first published in BEEF2026 – Driving Sustainable Performance, additional reading from BEEF2026 is available here.