First Cut Grass Silage: The Hidden Storage Risks That Can Cost You Later

For UK beef and dairy farms, first cut grass silage is more than just forage it is a winter ration foundation and a direct driver of animal performance. A good first cut is leafier, more digestible and higher in feed value than later cuts. But high-quality grass can still become poor-quality silage if storage is handled badly.

The frustrating reality is that silage losses are often invisible. The clamp may look full, the sheet may be on, and the crop may appear safely gathered but inside, feed value can quietly disappear through poor fermentation, heating, mould and dry matter loss. By the time the clamp is opened, the damage is already done.

Why Storage Matters as Much as Cutting Date

First cut silage season arrives under pressure. Weather windows are tight, contractors are busy, and the focus quickly shifts to getting the crop cut, wilted and clamped as fast as possible. That urgency is understandable but it is also where avoidable problems begin.

A silage clamp does not forgive rushed decisions. Grass that is too wet, too dry, soil-contaminated, poorly rolled or badly sealed can all lead to costly, preventable losses. The crop is not truly “made” when it leaves the field. It is only made when it has been properly preserved.

The Hidden Cost of Poor Silage Storage

Poorly stored silage does not just create waste at the clamp shoulders. The real cost is wider: lower feed value, reduced intakes, more bought-in feed, increased mould risk, dry matter loss and inconsistent rations all of which hit animal performance and farm profitability.

Think of a clamp as a feed bank. Every tonne inside it has cost land, fertiliser, fuel and labour to produce. Poor storage allows that value to leak away silently, every day.

Key Storage Risks to Manage

1. Cutting Height

Cutting too low increases fresh weight but drags in soil, raises ash levels and slows sward recovery. A slightly higher, cleaner cut often produces better silage. Harvest quality grass, not simply more bulk.

2. Getting Dry Matter Right

Dry matter is one of the biggest factors in successful clamp silage. Too wet and you risk effluent loss, poor fermentation and nutrient losses. Too dry and the grass becomes springy, traps air, and creates conditions for heating and mould. A controlled wilt to the right dry matter target is one of the most important calls in silage making.

3. Wilting With Purpose

Wilting should be deliberate, not left to chance. A fast, even wilt achieved through wide spreading and good airflow minimises field time and protects the sugars needed for effective fermentation. The longer grass lies on the ground, the more sugars are lost before the crop ever reaches the clamp.

4. Soil Contamination

Soil in the clamp is not harmless dirt. It introduces clostridial bacteria, raises ash content and reduces fermentation quality. It enters through low mowing, aggressive tedding, molehills and poached ground. Clean harvesting and correct machinery setup matter, the best clamps start with clean grass.

5. Clamp Filling and Consolidation

Modern foragers can easily outpace the clamp team. If grass is tipped faster than it can be spread and rolled, thick layers form, air pockets develop, and heating and dry matter loss follow. Thin, even layers and constant rolling are essential. A good clamp operator is building density and removing oxygen, not just moving grass around.

Poor consolidation also creates safety risks. Unstable, poorly compacted faces can collapse without warning. If trailers are arriving too fast, slow the flow, consolidation must always keep pace.

6. Clamp Shape and Shoulders

Spoilage rarely starts in the middle of the clamp. Shoulders, edges and the top are harder to roll and seal, and more exposed to air and water. Steep shoulders and uneven filling create weak points. The best clamp is not the fullest clamp, it is the one that has been filled, rolled and sealed in a way that protects the crop throughout.

7. Sealing: Do Not Rush the Last Step

Sealing is one of the most important parts of preservation. Oxygen entering through poor sheeting, loose edges, holes or inadequately weighted plastic allows spoilage organisms to remain active long after the clamp appears closed. Use quality oxygen barrier film, pull sheets tight, weight the full surface and check regularly for damage from birds, vermin or weather.

8. Effluent Management

Effluent is not just a nuisance, it is feed value leaving the clamp. Wet silage is the main driver. Before silage season, check that drains are clear, channels are working, tank capacity is adequate and the clamp floor is sound. These are not glamorous jobs, but they protect both your feed and your environmental compliance.

9. Additives - Useful, Not a Fix

Silage additives can support fermentation and improve stability, particularly in challenging conditions. But they cannot compensate for contaminated grass, incorrect dry matter, poor rolling or bad sealing. The fundamentals matter most. Additives work best when the basics are already right.

10. Feed-Out: The Risk Starts Again

Many farms work hard to make good silage, then lose quality at feed-out. Once the clamp is opened, oxygen is reintroduced. Keep the face clean and tight, remove silage evenly, avoid exposing more than needed and always remove visibly spoiled material rather than mixing it into the ration. A tidy clamp face is not just about appearance — it directly protects feed quality and animal intake.

First Cut Silage Storage: Quick Checklist

Before Cutting

•      Inspect clamp walls, floor and drains - repair before the first trailer arrives

•      Remove old spoiled material from the clamp

•      Prepare side sheets, top sheets and oxygen barrier film

•      Walk fields for molehills, poaching and contamination risks

•      Agree dry matter target and plan harvest around the forecast

During Harvest

•      Avoid mowing too low - prioritise clean grass over maximum bulk

•      Wilt quickly and evenly; minimise time on the ground

•      Keep tedders and rakes correctly set to avoid soil contamination

•      Spread grass in thin, even layers and roll continuously

•      Keep the clamp team focused on consolidation, not just speed

After Filling

•      Sheet the clamp quickly and ensure close contact between sheet and silage

•      Weight sheets thoroughly across the full surface, especially shoulders and edges

•      Check for and repair sheet damage promptly

•      Monitor for effluent, movement or visible spoilage

At Feed-Out

•      Keep the clamp face tight and remove silage evenly

•      Avoid exposing too much silage at once

•      Remove spoiled material - never mix it into the ration

•      Watch for heating, mould or unusual smells

•      Maintain a safe working distance from high or unstable clamp faces

Good Storage Is Good Business

With fertiliser, fuel, contractor and labour costs all rising, the real cost of every tonne of silage made has never been higher. Poor storage is more expensive than it used to be.

The farms that consistently make better silage do the basics well. They cut cleanly, wilt with purpose, consolidate properly, seal carefully and manage the clamp face with discipline. It is not complicated but it does require attention at every stage.

First cut grass silage is too valuable to gamble with. Protecting forage quality is not just good farming practice on tight margins, it is essential business management.