Treading lightly: protecting soils after a wet winter

Date published: 12 March 2026

Many farms in Northern Ireland have a mix of heavy clay and clay loam soils, which are slow to drain and highly susceptible to structural damage when trafficked in marginal conditions. As slurry and fertiliser applications commence, it is critical that farmers consider the impact of machinery on soil structure. The focus must be on protecting long-term soil productivity while still meeting early season nutrient demand.

Soil compaction remains a significant challenge for grassland farms, with long term implications for productivity and nutrient efficiency.  When soil becomes compacted, the reduction in pore space limits oxygen availability, restricting root development and slows the natural movement of water through the soil. These conditions can have immediate and measurable impacts on performance including:

• Reduced grass growth and poorer nitrogen response leading to lower forage availability when it is needed most.
• Delayed livestock turnout as compacted soils dry more slowly and struggle to recover from winter conditions. 
• Increased surface runoff and nutrient loss, reducing fertilizer efficiency and increasing environmental risks.
• A decline in soil biological activity, affecting long term soil health and resilience.
• Lower grazing efficiency through poaching risk, particularly in high traffic areas and during wet periods. 

These effects demonstrate the importance of pro-active soil management as farmers enter the busy spring season. Soil compaction can significantly reduce dry matter yields with AHDB studies estimating a yield reduction of between 14% and 22% on compacted soils. On farms operating tight grazing rotations and high stocking rates, even small reductions in early growth can impact silage quality and overall system performance.

Following prolonged rainfall, soils across the region are at or near field capacity. Many fields show shallow surface smearing from winter feeding or late grazing. 

Farmers should try to prioritise drier, free-draining fields first and avoid repeated runs over headlands. If multiple passes are required, for example to apply artificial fertiliser straights then try to use the same rollings as the previous time.

Delaying field work for several days in improving weather can prevent damage that may persist for years. Where ground conditions remain marginal, farmers may consider:

• Umbilical slurry systems to reduce in-field axle loads 
• Smaller tanker loads where practical 
• Applying slurry to silage ground first and fertiliser to grazing ground
• Splitting nitrogen applications to reduce single-pass weight     

Preventing compaction is more effective than attempting to correct it. Mechanical subsoiling is costly, and often unsuccessful on heavy clay soils unless carried out in ideal dry conditions.

Improving soil organic matter through nutrient management, maintaining appropriate pH and avoiding overgrazing in wet periods will increase structural resilience over time. However, tyre pressure management and being conscience of axle loads remain two of the most immediate and controllable actions available this spring.

Where soil has not fully restructured over winter, trafficking with loaded slurry tankers presents a real threat of both surface and sub-surface compaction.

Damage to soil is influenced by two factors, total axle load and tyre inflation pressure. While machinery size has increased over recent years, tyre technology has also improved. The key principle remains simple: tyre inflation pressure largely determines the pressure exerted on the soil surface and axel load will affect the depth to which the effect is transmitted into the soil profile

Before carrying out fieldwork, farmers should:

• Check tyre manufacturer load and inflation tables for correct pressure setting.
• Adjust pressures to field settings before entering fields.   
• Ensure axle loads are within tyre capacity at lower pressures.

If a tyre is inflated to 35–40 psi for road transport and enters a soft field without adjustment, similar pressure is exerted onto the soil. On saturated clay soils, this results in rutting, surface sealing and structural damage below ground.

Reducing tyre pressure increases the tyre footprint and spreads the load over a greater area. This significantly reduces the risk of compaction in vulnerable conditions. As a guide, reducing tyre pressure from 40 psi to 18–22 psi in field conditions can substantially increase the contact area. However, pressures must remain appropriate for load and speed. Under-inflation beyond recommended limits risks tyre failure and safety issues.

Many tyre manufacturers are now offering Very High Flexion Tyre (VF) designs.  These are specifically engineered to operate safely at lower inflation pressures while carrying heavy loads. Their flexible sidewalls and increased air volume create a larger footprint and reduce soil stress. Their ability to work at reduced pressure across a wider speed range than conventional radial tyres particularly suits operations that combine road and field work like slurry spreading.

In Northern Ireland VF tyres are particularly beneficial where:

• Field work is being carried out early in spring.
• Axle weights exceed 6 tonnes. 
• Contractors using large equipment. 
• Fields have imperfect drainage. 

Although these tyres carry a higher upfront cost, the investment should be viewed in the context of long-term soil productivity. However, even with improved tyres, timing remains critical.

Protecting soil structure is not simply an environmental measure, it is a direct investment in grass production, nutrient efficiency and whole-farm profitability. The decisions made over the coming weeks will influence performance for the remainder of the season and beyond.  For further information visit the business support area of the CAFRE website or contact your local CAFRE Adviser.