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Good silage clamp management this season will maximise forage quality – more than justifying at a time when nitrogen fertiliser prices is at all-time... 5 ways to ensure your silage clamp remains airtight

Good silage clamp management this season will maximise forage quality – more than justifying at a time when nitrogen fertiliser prices is at all-time high.

“Inadequate sealing not only results in poor fermentation and forage spoilage, it also means much of the money spent on nitrogen and other inputs has been wasted, says Lucy Johnson of film specialists Silostop.

“Considering the downsides, it is worrying that so many people still use a range of variously-sized black plastic sheets and a few worn-out tyres with rusty wires thrown on top of the clamp.”

Few farmers would tolerate 15% storage losses for any other crop, says Ms Johnson. Yet that is often the case with forage. But such losses can be kept within 5% by following some simple steps:

1 – Plan sealing priorities carefully
The starting point is to talk to a specialist and work out exactly how are you are going to seal the clamp and what you will need to do this.

“You’ll need to know the exact dimensions of your clamp to do this. The most effective method is a single sheet system, but these are available in range of sizes and the best fit will depend on individual circumstances.

“The intention is to keep the number of joins to a minimum to avoid potential air ingress, so a purpose-made side sheet is essential too.”   

2 – Using a proper oxygen barrier 

It is important to understand not all plastic sheets are created equal, explains Ms Johnson.

“A proper oxygen barrier has an oxygen transmission rate less than 5cm3/m2 of film, which means almost no air can get into the clamp, but with typical black silage plastic this is more like 300cm3/m2 .

“When this is stretched out to make an imitation oxygen barrier cling film, it can reach 1000cm3/m2 so quite a lot of air is able to pass through the film resulting in considerable spoilage and dry matter shrinkage in the top layers.

“Again, you need to talk to somebody who understands this and be prepared to ask the questions about oxygen transmission rates. A good film will virtually eradicate air from the clamp, a cheaper one could cost you dearly in terms of lost forage.”

3 – Minimise plastic

A modern single sheet system will not only minimise forage wastage, it will also help ensure you are using as little plastic as possible on-farm.

“Nobody wants to use more plastic than they need to. On a typical 16m wide by 50m long clamp, conventional black plastic with cling film will weigh around 110 kg, whilst with our most popular single sheet Silostop Max, this would be only 66kg.

“Furthermore, if you were to use an Anti-UV cover over a thinner film  such as Silostop Orange, the weight could be reduced to 38kg – which is a reduction in plastic use of 65% compared to the traditional approach. All our films are 100% recyclable too.”

4 – Manage films correctly

Type of forage will also play a key role in choosing the optimum film.

“If you’re using a multi-cut system, where you will be repeatedly opening the clamp up to add material, a stronger film is advisable. This can then be used with a secure cover.

“If you’re clamping maize or wholecrop silage where the clamp is filled and then left until it is opened, the lighter sheets with an Anti-UV cover are the best option. 

Whichever approach you take, bags and purpose-made mats are the best materials for keeping covers in place and minimising pest damage.

“The other advantage is that sheeting time can be cut in half and that’s important in making sure clamps are sealed every evening when you are filling them and also whenever you remove material from it over the winter.”

5 – Constantly review performance 

Keep an open mind about how you can improve the efficiency of your silage making in the future.

“We’re learning more about the best way to make silage all the time and when the cost of inputs and bought-in feeds is rising so quickly, it’s essential to make full use of every kg of forage you produce.

“With home-grown forage increasingly critical to the economics of dairy production, investing in the best film you can, will always create a significant return on investment.”