Silage Season: Managing First Cut in an Unpredictable Spring

06 March 2026

As the rain finally begins to ease across the UK, dairy farmers will be glad to get slurry onto fields and relieve the pressure on bulging slurry stores.

Although the closed spreading period ended over a month ago, persistent wet ground conditions have made it impossible for many farms to apply slurry to grassland. Dairy regions such as the South West of England, Ireland and northern upland areas have been among the worst affected, with rainfall totals in some areas reaching more than double the long-term average over the past six months.

However, as one problem is solved, another begins to appear. With slurry applications delayed, cutting dates for first-cut silage will now be much closer to the timing of nitrogen application. This can lead to elevated nitrogen levels in the crop, particularly if farmers are tempted to cut early to replenish already depleted silage stocks following the dry summer previously.

As is often the case in farming, the right management decisions are needed to reduce the impact of environmental conditions. Looking ahead, three broad spring scenarios could unfold across UK grassland systems over the coming weeks. With increasingly unpredictable weather patterns, long-range forecasts cannot reliably say which will occur, but preparing for each will help protect silage quality.

1) The Sodden Spring

In this scenario, temperatures remain on the cool side and rainfall continues well into late spring. Grass growth is slow to start and field conditions make it difficult to apply slurry or fertiliser evenly.

Cutting dates are delayed, meaning grass will become more mature before harvest. While yields may be reasonable, digestibility and energy content decline as fibre levels increase. Delaying the first cut also delays subsequent cuts and often pushes the last cut too late in the season, or it might be dropped entirely.

Wet conditions also make it harder to achieve adequate wilting. This is especially the case when harvest is delayed, as a larger crop is on the ground to dry.

Grass ensiled at low dry matter (below around 25% DM) carries a higher risk of undesirable fermentations, particularly from clostridia. These bacteria thrive in wet conditions and can lead to:

  • Butyric acid production
  • Excessive protein breakdown and ammonia formation
  • Poor silage intake by livestock
  • Reduced feed value

Wet spring silage also ferments more slowly because the crop contains less sugar relative to moisture, and lower temperatures slow the activity of beneficial bacteria. This makes it harder for lactic acid bacteria to produce the lactic acid required for the rapid pH drop needed to stabilise silage.

Where weather allows, farmers should aim to maximise wilting opportunities, even if the window is short. Wilting periods should generally be kept to no more than 24 hours unless strictly necessary. Conditioning, tedding and turning the crop can all help reduce the time needed to reach the desired dry matter.

Targeting 30–35% dry matter, ensuring tight consolidation in the clamp, and sealing quickly to exclude oxygen will all help create the right conditions for stable fermentation. A silage additive should always be used, and in more challenging crops some farmers may also consider a specialised biological silage additive to help support a faster and more controlled fermentation.

2) The Steady Spring

If temperatures and rainfall settle around seasonal averages, grass growth could be strong thanks to the high soil moisture levels built up over winter.

In this situation, farmers may see a relatively early first cut, particularly if warmer temperatures arrive during April and early May.

However, because slurry applications have been delayed, nitrogen levels in the crop may be higher than usual. Grass cut too soon after slurry or fertiliser application can contain elevated nitrate levels.

High nitrate crops can influence the fermentation process because nitrates act as a buffer, slowing the drop in pH that is required to stabilise silage. This can result in slower fermentation and a pH higher than required, leading to increased breakdown of plant proteins.

To minimise the risk:

  • Allow sufficient time between slurry or fertiliser application and cutting where possible
  • If slurry or fertiliser application is delayed, consider reducing the amount applied so that it will be out of the crop by the usual cutting time
  • Aim for a good wilt (around 30–35% DM) to concentrate sugars and support fermentation
  • Harvest grass at the optimal growth stage rather than chasing maximum yield

Bear in mind that a well-balanced crop with adequate sugars and the correct dry matter will ferment far more efficiently, even where nitrogen levels are slightly elevated.

3) The Sudden Summer

UK springs sometimes shift abruptly from wet winter conditions to warm, dry weather with very little transition.

In this scenario, rainfall stops quickly and warmer temperatures combined with strong sunlight accelerate grass growth. With soil moisture levels already high following the wet winter, crops may respond rapidly and reach cutting stage earlier than expected.

Drier weather will improve wilting conditions and field trafficability, giving farmers greater flexibility around harvest timing.

However, rapid early growth can produce lush grass with relatively high nitrogen levels and lower structural fibre. If crops are cut very early, they may still have an unexpectedly high moisture content and relatively high buffering capacity, meaning fermentation still requires careful management.

Farmers should aim to:

  • Avoid cutting too soon after nitrogen or slurry application, or apply a lower rate if application is delayed
  • Achieve a good wilt to increase sugar concentration
  • Ensure rapid clamp filling, consolidation and sealing to exclude oxygen

Remember that warm weather can also increase the risk of aerobic spoilage during feed-out, so achieving a stable fermentation and maintaining good clamp management remains essential. Using high-quality oxygen-barrier films will help reduce air ingress and preserve silage quality during both storage and feed-out.

Regardless of which weather surprises unfold, the key things farmers should try to influence to protect silage quality remain the same:

  • Crop dry matter at harvest
  • The balance of nitrogen and sugars in the grass
  • Rapid exclusion of oxygen during ensiling

Simple management tools from good harvesting practices through to modern silage additives and effective clamp sealing all play a role in protecting the nutritional value of the crop.

By paying close attention to these factors and adjusting management as the season unfolds, farmers can protect forage quality whatever the weather has in store this spring.

 

CONTACT REALISTIC AGRI FOR FURTHER ADVICE:

WALES: Gareth 07927 288866

SCOTLAND & IRELAND: David 07766 722502 / +353 85 224 3454

ENGLAND: Sean 07714 213455 or Adam 07494 435031