Red Clover Silage

Silage crops are fertiliser-hungry and often inefficient.
Red clover cuts nitrogen needs and produces high-quality, protein-rich forage for silage.

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The Climate Issue

Silage is preserved grass used to feed cows in winter when grazing isn’t possible. But producing it causes high emissions. Grass silage needs a lot of nitrogen, up to 300 kg N/ha in some systems. That fertiliser releases nitrous oxide, ammonia, and raises the risk of nutrient runoff.

Using high levels of inputs also harms soil, lowers clover levels, and gives uneven protein content. Cutting and wilting need more machinery passes, which increase fuel use and cost.

All this makes silage one of the highest-emission parts of dairy feeding.

The Solution: Red Clover

Red clover is a deep-rooted legume ideal for silage production. It fixes its own nitrogen, cutting the need for synthetic fertiliser, while delivering high dry matter yields and strong protein content.

With proper establishment, red clover silage can yield 12-16 t DM/ha, with crude protein levels of 14-17 %. And it requires up to 200 kg less nitrogen per hectare. It’s especially suited to multi-cut silage, improving forage quality and lowering emissions at the same time.

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Key Benefits when using Protected Urea

Cut Emissions

Red clover fixes nitrogen, reducing reliance on synthetic N. That lowers GHG emissions and ammonia loss from fertiliser spreading.

High Protein

Red clover silage delivers more dry matter and higher protein than grass-only silage, supporting milk solids during winter feeding.

Soil Health

Its deep roots boost soil structure, resist drought, and add organic matter back into the soil, making it a regenerative option for forage.

Impact of Switching to Red Clover Silage

Switching to red clover in silage systems is a proven way to cut fertiliser use, reduce greenhouse gas emissions, and improve forage quality. It’s particularly valuable for farms aiming to reduce their reliance on synthetic nitrogen while maintaining milk output during housed periods.

Teagasc trials and the Farm Zero C case study show that red clover can:

Replace up to 150–200 kg N/ha in multi-cut silage systems
Save €100–€200/ha in fertiliser costs (compared to CAN)
Cut GHG emissions by 4–8%, depending on adoption rate
Improve milk yield and solids during the winter housing period

See the table below for how red clover adoption affects emissions and fertiliser costs on a 20-hectare silage block. Initial reseeding costs must be considered.

Scenario	Red Clover Area	Fertiliser Savings / 20 ha	GHG Emissions	% GHG Reduction
0% Silage Area	-	-	0.960 kg CO₂-eq/kg milk	0%
50% Silage Area	10 ha	€1,000	0.921 kg CO₂-eq/kg milk	4.1%
100% Silage Area	20 ha	€2,000	0.881 kg CO₂-eq/kg milk	8.2%

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Considerations

Lifespan & Rotation

Red clover is short-lived, typically 3-4 years. It suits silage rotations but should be managed to avoid overgrazing or damage in wet conditions.

Cutting Management

Red clover silage should be cut before full flowering. Delayed cutting reduces quality. Avoid cutting too low to preserve regrowth.

Bloat Risk & Inclusion Rate

When grazed (not typical), bloat can be a risk. Stick to silage-only systems or manage carefully in mixed swards.

Implementation

Red clover fits easily into silage ground and delivers fast returns. With the right establishment and cutting routine, it becomes a high-performance forage option. Here’s how to get started.

1. Choose a suitable site. Avoid poached or heavily trafficked fields. Select paddocks due for reseeding and rotate every 3–4 years.

2. Prepare and sow. Aim for pH 6.3+, and Index 3 for P and K. Sow in spring or early autumn with a suitable grass companion (e.g. Italian ryegrass).

3. Cut correctly. Take the first cut before flowering. Leave a 6 cm stubble to protect crowns. Apply slurry after cuts, red clover needs no additional nitrogen.

Behind the Research

ODOS Tech was founded by Cian White and Alejandro Vergara, two sustainability specialists with deep expertise in agricultural climate action.

Alejandro (left), a PhD in environmental engineering from University College Dublin, helps farmers measure their carbon footprint and implement mitigation strategies to reduce their impact. Cian (right), a researcher at Trinity College Dublin with a PhD in ecology, works on restoring nature to increase biodiversity on farms using satellite imagery to monitor habitats.

Together, they helped lead the carbon and nature-based work for the Farm Zero C project at Shinagh Farm, one of Europe’s first net-zero dairy pilots. In 2020, they launched ODOS, a platform that built smart, science-based tools to help agri-food businesses protect the environment and restore nature.

Research

Teagasc Red Clover Silage Trials

Teagasc trials show red clover yields match or exceed conventional silage, even with 70 % less synthetic N. Crude protein is 2-3 % higher than grass-only silage.

Farm Zero C Implementation

At Shinagh Farm, red clover was integrated into silage areas with strong results. Lower fertiliser use, improved forage quality, and steady milk production over winter.

Policy Support

Red clover is supported under many eco-schemes for nutrient efficiency. It aligns with EU and CAP targets for reducing fertiliser inputs while maintaining feed quality.