Adapting silage making to dry weather

Dry weather is becoming increasingly common across the UK. Make practical changes to cutting height, timing and additive use to help protect silage quality during dry spells.

Drought-stressed grass has:

• Lower yields, meaning reduced silage volumes
• Lower water-soluble carbohydrate (WSC) levels, which can hinder fermentation
• Higher fibre content and reduced digestibility, particularly if the crop has gone to seed
• Lower moisture content, increasing the risk of poor fermentation or mould

Recognising these risks is the first step towards adapting silage-making methods to maintain quality, despite lower biomass or compromised grass growth.

Raise cutting height to 7–8 cm during dry weather (compared to the usual 5 cm). This helps protect the sward and improve silage quality.

Grass relies on basal reserves during dry periods. Cutting too low removes these reserves and slows recovery.

Dry soils are more likely to contaminate forage with dust. A higher cut reduces soil ingress and unwanted microbes.

Cutting too low in dry conditions increases the risk of long-term damage to perennial species.

This is especially important for perennial rye-grass leys or shallow-rooting species, which may already be under stress.

Cut slightly earlier than usual, focusing on quality over bulk.

Watch for stem elongation and heading. Grasses may head earlier in dry conditions, so harvest before seed heads appear.

Avoid over-wilting. Crops are already dry, so wilting for more than 12–24 hours may reduce moisture too far.

Target dry matter (DM) levels:

• 28–32% for clamp silage
• 35–45% for baled silage

Monitor sugar levels using a refractometer or rapid test kit. If sugar levels are below 2%, fermentation may be compromised without intervention.

Mow during the coolest part of the day to reduce plant respiration losses and preserve sugars.

Using weather data and decision support tools can also help time cuts better around forecasted rainfall or heat.

When sugar levels are too low or pH buffering capacity is high, such as in clover-rich swards, additives become essential.

Application tips:

• Match the additive to the crop and ensiling conditions
• Apply evenly to avoid patchy fermentation
• For bales, use enough wrap layers to prevent spoilage, especially in drier, more aerated bales

Dry forage is harder to consolidate. Roll in thinner layers and use a heavier roller or longer rolling time.

Aim for high-density bales to limit oxygen ingress.

Drought increases the risk of compaction from machinery. Keep machinery passes to a minimum and use wide tyres or duals where possible.