How long can you safely store silage and still have a product that has reasonable feed value? There are stories of silage being stored in excess of 25 years and it still having a value but it’s unlikely you would plan for this in a European climate. The silage harvest of 2020 is drawing to a close and in general the yields and quality have been reasonable across much of the UK. It’s certainly a much better situation than the poor grass harvest caused by low rainfall in 2018.

Weather such as the 2018 summer drought was considered extreme and “one off event”, but these one-offs seem to keep coming. We have had extremes of wet, dry and cold in the past decade and there seems to be no return to traditional weather patterns on the cards. That means farmers and growers are having to change the way they think and their cropping plans. Now for the farmers of Australia (for example) this is standard practice. In many parts of the world weather – or more importantly rain – are not predictable and farming practices have to be tailored to suit the climate accordingly.

So given we are going to face varying climate, you will face varying yields from forage crops in the future. So the natural reaction to this is to “make hay when the sun is shining” and stockpile silage in the good seasons to tide you over in the poor years. But is this a good solution and what can you do to improve the chances of having something of value when you finally start feeding the banked forage?

Will silage spoil over the long term?

Silage is – as we have covered previously – a living product in a suspended state. The degradation of feed value of the silage is reduced if you can create the correct conditions within the clamp. Low pH and an absence of oxygen will halt almost all the microbial activity that will otherwise turn your silage into compost. That’s a nice sentence – except for the almost, and that’s the problem. If you long term store silage, there will be inevitable losses of the feed value, the trick is to keep these losses to a minimum and plan accordingly.

In essence the rules for making long-term silage are the same for any good silage. Get the target dry matter correct, chop and ensile by the rulebook and seal the clamp well and you have expect a palatable silage for the long term. The Australian beef farmer who opened up that 26 year old sorghum silage must have done the job pretty well because in analysis, the silage still had 7.5% protein levels. The silage was stored in a hillside clamp and this probably helped by stabilizing the temperature within the clamp. It’s unlikely you are making sorghum silage in Europe and the SSAFO regulations don’t allow you to make an earth bunker anymore, but what can we learn from this case? 

Planning for long term silage storage

The real key to long-term silage storage is to plan ahead. To store silage for a long period, you need the best storage conditions so a temporary or field clamp is only be considered for short term storage. Once you have a yield estimation, plan the harvest accordingly and decide where you can store additional material. Next think about how you are going to seal the clamp. All silage needs airtight covering but traditional black plastic is broken down by UV light so you are going to need a “sheet” that will be stable in the elements. You also need to protect the seal sheet from bird and rodent attack and from storm damage. Once you’ve done this you can’t just forget it, you need to keep monitoring the clamp and repair any breaches of the airtight seal.

You might also need to think about the costs of long-term storage. Planning for long-term storage is a bit more than just having some left over when we get an early spring and the cows go out to grass a little sooner than expected. Planning for long-term storage will require more clamp space and this comes at a cost. There is also a cost in the losses of the silage over the storage time.

What other options do you have? 

This really comes down to economics, at the end of the day the feed value of silage has to compete with any other product that contains equivalent feed analysis. In a dry year if it’s cheaper to reduce the forage composition of a ration and top up with straights then that’s the solution. Unfortunately the climate affects us all and so the relative costs of different materials are impossible to factor in before the event. In a dry year everyone wants brewers grains or sugar beet pulp and the price reflects that.  You can budget for the costs of “extra” silage though so it’s a more predictable feed stock.

 How long can you store silage?

You might not want to plan for the 26 years storage of silage like the farmer in New South Wales but how long is reasonable? The losses seem to suggest that about 3 years is a realistic target. Once silage has been in the clamp longer than that, you really need to plan how you can use it up before it loses too much value. After all you have already spent the money to produce it, you need to use it before the value has gone.

If you want to discuss long terms silage storage or for more information on any of the other aspects of silage making covered in this series – contact Jeremy Nash at jeremynash1@btinternet.com

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