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Grass harvest

Grass harvest for making silage

As I was cycling along the Breamish Valley yesterday (hottest day of the year so far) and today, I noticed that a grass harvest had begun on two of the farms near Brandon.

During the summer months grass grows vigorously and it’s typically harvested by stock farmers (usually keeping dairy cows, beef cattle and sheep) to make silage. Warm, dry weather is ideal for harvesting grass for making silage.

What is silage?

Silage is pasture grass that’s been fermented. First, the grass is mown. It’s then left in the field for several hours to wilt. This reduces the moisture content. The grass is then collected and either kept in a heap in a farmyard, and compressed to remove as much air as possible, or else rolled into large, tightly compressed bales. Whichever method is used, the grass is then covered (or wrapped) in plastic sheeting and sealed to eliminate as much oxygen as possible. Over several months, bacteria in the grass effectively ferment it. The bacteria break down sugars in the grass to form lactic acid. As the acidity of the grass increases to around pH 4-5, the sugars are no longer broken down and the grass is preserved. Once it’s opened and exposed to more oxygen, the grass will begin to deteriorate. The silage remains high in nutrients and it’s used as winter feed for stock animals.

First step: mowing


Mowing pasture for grass harvest in the Breamish Valley

After mowing, the grass is sometimes spread in order to encourage a better wilt. As mentioned above, wilting is necessary to remove excess moisture.

spreading grass

Spreading grass before grass harvest to get a better wilt

Second step: rowing out

If the mower used to cut the grass didn’t automatically lay the grass into rows (known as swaths), then this will need to be done. It’s assembled in rows so that the harvesting machine can pick it up.

swaths of grass

Swaths of grass near East Hill, Branton, Breamish Valley

Third step: harvest

Depending on the method to be used for making the silage, the grass harvest is slightly differently.

If it is to be baled, a round baler is used. This collects the grass from the swaths, loads it immediately into a baler chamber on the harvester and rolls it into large, compressed bales. These are typically around 1.5 meters in diameter. The bale is then sealed in plastic sheeting and stored for use in winter.

In contrast, if the grass is to be stored in the farmyard (perhaps in large bunkers or clamps), the forage harvester picks it up from the swaths and chops it into small lengths. In some cases a trailer is towed by the harvester itself. In other instances, another tractor and trailer drives alongside the harvester and the chopped grass is blown straight into the trailer. This can then be taken away to the farmyard to be laid in a heap and compressed to make the clamp silage.

forage harvester and trailer

Forage harvester blowing cut grass straight into separate trailer
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