Production of high quality grazing forage in pasture-based dairy systems is important in ensuring high productivity. Incorporating white clover in the grasslands is significant in reducing greenhouse gas emissions and costs associated with fertiliser use.
Overview
White clover is a leguminous plant which has nitrogen fixation capabilities thus reducing the chemical fertiliser requirements in grasslands. White clover is suitable for grazing and persists for 3-8 years.
Why should I Increase clover content in a dairy paddock?
Grasslands with at least 25% clover have the following benefits.
- Increased dry matter production.
- Reduced chemical nitrogen fertiliser use.
- Increased dry matter intake and milk solids production.
- Increased farm profit by €150/ha.
- Compliance with policy.
In the following video, a farmer explains the benefits and challenges of white clover.
https://youtube.com/watch?v=lwtwl6OegSsr
How do I include white clover in my grassland?
- White clover can be established by either oversowing or reseeding.
- Sow in moist soil conditions in highly fertile soil and pH of 6.3. When reseeding, broadcasting is highly recommended.
- Mix the white clover seed with grass seed and compound fertiliser and sow immediately to ensure even spread.
The following video provides details on oversowing white clover. –Oversowing clover
- For grazing management, ensure a pre-grazing herbage mass of 1300-1600kg DM/ha and a post-grazing sward height of 4cm (50kgDM/ha).
- Avoid overgrazing and winter damage.
The following video provides details on the management of established grass-white clover swards.
More on white clover establishment and management
Economic and Environmental Benefits
Incorporating white clover reduces the demand for chemical nitrogen fertiliser. Table 1 below shows the annual savings and reduction of emissions for a typical 31-ha farm under different scenarios.
Table 1 Net annual savings and emission reductions from grass-clover swards
| Scenario 1 Grass only | Scenario 2 Grass- clover (25% of the area) | Scenario 3 Grass-clover (50% of the area) | Scenario 4 Grass-clover (100% of the area) | |
| Grazing area(ha) | 31 | 31 | 31 | 31 |
| Average nitrogen fertiliser used (kg/ha) | 250 | 225 | 200 | 150 |
| Fertiliser savings (€) | – | 1868 | 3720 | 7440 |
| Extra reseeding costs (€) | – | -248.3 | -497 | -987 |
| Net savings/farm(€) | – | 1619 | 3223 | 6453 |
| Net savings/ha(€) | – | 52 | 104 | 208 |
| Environmental impact | ||||
| Total Emissions (kg CO2-eq / kg FPCM) | 0.95 | 0.94 | 0.93 | 0.90 |
| Reduction in emissions (%) | – | 1.16 2 | 2.42 | 5.16 |
The stocking rate is 2.5 LU, and soil drainage is average
The 2022 fertiliser prices of €750/t for CAN and €950/t for Urea were used.
Net savings/ cost are the savings or costs per year for the farm
Research
Research at Farm Zero C
Grass-white clover swards have been implemented in some grazing paddocks with the objective of reducing chemical nitrogen fertiliser to 150kg/year over the lifetime of the swards. The target is to have 27% clover cover in 25% of the paddocks by 2023. The clover inclusion so far covers 10% of the grazing area.
Other Research
Previous research in Ireland has highlighted the following key findings.
- The inclusion of white clover in Perennial RyeGrass (PRG) increases dry matter production and reduces nitrogen fertilizer use (Moloney et al., 2021).
- At > 25% white clover inclusion, dry matter intake increased by 1.5 kg DM/cow/day, while milk solids production increased by approximately 30 kg MS/cow (Egan et al., 2018).
- The PRGs-clover swards reduced methane emission intensity by 12% (Smith et al., 2021).
Links to more research
Introducing white clover into existing swards and getting variety of choices right
The effect of perennial ryegrass ploidy and white clover inclusion on milk production of dairy cows
Regulations
Including white clover as a strategy is important to meet the regulations listed below.
The Nitrates and water directive
The nitrates derogation– For derogation farmers, all new grass reseeds on the grassland farm shall incorporate at least 1.5 kg/ha of naked clover seed or at least 2.5 kg/ha of pelleted clover.
The Ag Climatise roadmap 2021– The inclusion of white clover in grasslands supports the following actions of the roadmap to climate-neutral agriculture.
- “Action 1: Reduce chemical nitrogen fertilizer use by 40% by 2030.”
- “Action 4: Maximise production of grazed grass.”