Every summer the countryside takes on an unusual look, as large black plastic objects appear in the fields. They are silage bales and, while they might look strange, they are vital in ensuring that livestock have plenty of food over the winter.
What is silage?
Silage is grass that’s been cut in late May or early June and then preserved by pickling, in much the same way as you might pickle vegetables in the kitchen. The perfect anaerobic conditions have to be created – by removing the oxygen the grass starts to ferment, converting natural sugars into acid.
Farmers grow grass for silage because it’s both a cheap way of feeding their animals and gets the maximum use out of their grassland.
Silage is a major food source for cattle and sheep that’s packed with energy, protein, vitamins and minerals. Plenty of ryegrass and clover in the mix helps get the balance right. Silage can be the basis of livestock diet right through the winter months when grazing is impossible.
When was silage first made?
‘Ensilage’ is a French word that simply means preserving green fodder in a silo or pit. First used in Germany 200 years ago, the process caught the eye of the French agriculturist Auguste Goffart who wrote a widely respected book about the technique. It was picked up by dairy farmers in America in the 1870s and within a few years was introduced to the UK.
The ease and efficiency of silage making is why hay bales are seen less often these days. Good hay-making relies on warm weather (the crop needs to dry in the sun), which is often in short supply in the British Isles!
How is silage made?
An agricultural mower first cuts the grass in the field into lines (or swaths). These are then gathered by a forage harvester, fed into a chopper and blown into a trailer.
There are two ways to ferment the grass: the old way is to pile it into a heap known as a clamp and drive a tractor over it repeatedly to compress it. To keep it airtight, it is covered with plastic sheeting that’s weighed down, often with hundreds of old tyres.
The other is to wrap cut grass into bales covered in plastic, which are easy to stack.
So if you spot those huge plastic-covered bales in the fields, remember that they could end up as Christmas dinner for the nearest herd of cattle.
