How to achieve a faster silage wilt

Ecosyl UK research has found that selecting the right wilting technique when making grass silage can speed up the process by up to five times. The research, which was conducted on farms in Wales using farm-scale silage machinery, compared the effects of tedding, time of day of cutting, and crop maturity on the rate of crop drying.

The results showed that tedding the grass after cutting increased the rate of wilting by up to 30%. Cutting the grass in the morning also resulted in faster wilting, as the dew on the grass helped to cool it down and reduce the rate of evaporation. Finally, the research found that the most mature grass wilted the fastest, as it had a higher water content.These findings suggest that farmers can speed up the silage wilting process by using the right techniques. Tedding the grass after cutting, cutting it in the morning, and harvesting the most mature grass will all help to reduce the amount of time it takes to make silage.

Findings from a first trial in Pembrokeshire on a light, multi-cut grass crop cut on a warm, dry July day revealed that cutting at 10am and tedding immediately resulted in grass reaching a target dry matter (DM) content of 30% in just 4.5 hours. That compared with 7 hours to reach 30% DM if grass was not tedded until 5 hours after cutting, or a full 24 hours if grass was left untedded in rows. 

When grass was cut at 3pm and tedded immediately, it reached 30% dry matter (DM) in 5 hours. However, it took 23 hours to reach 30% DM when it was not tedded until the following morning. When the 3pm cut was left untedded, it failed to reach 30% DM at all, even after 24 hours.

“Results overall showed that the average drying rate of 1.0% DM per hour for the grass cut at 10am and tedded immediately was five times faster than the rate of 0.2% DM per hour for the grass cut at 3pm and left in rows,” explains Ecosyl silage scientist, Dr Mark Leggett. “This is highly relevant as farms strive to increase milk production from homegrown forage and silage, because the longer that grass is wilted for, the more nutrients it will lose.” 

Ecosyl silage advisor, Peter Smith, agrees and says the benefits of wilting are not only that it reduces the risk of clamp effluent, but also that it produces a more nutrient-dense silage, improves silage intakes, and reduces the acid load produced during the fermentation.

Wilting grass to 28-32% dry matter (DM) is the best balance between minimizing effluent and field and clamp losses, he says, but wilting should be done as quickly as possible because the nutritional quality of grass starts to decline as soon as it is cut.

“Sugars and proteins are degraded by the grass, but undesirable micro-organisms present will also multiply up and feed on the sugars and break down the protein,” says Mr Smith.

“There are various views about whether grass should be cut in the morning or afternoon, but ultimately it is a race against time to wilt and ensile as rapidly as possible. Lost silage energy equates to lost milk.”