TIPS FOR TOP PITS
ENSURE good fermentation by using the right additive, filling the clamp with care, avoiding excessive rolling and sealing the pit quickly.
This is the advice from Wiltshire-based Genus consultant Neil Adams. He recommends using inoculant silage additives particularly for dairy cows for it increases dry matter intake and milk yields.
"Research has shown that on most normal grass crops inoculants work well," he says. "You dont need to use acids except perhaps on low sugar grass or when there is a high risk of soil or slurry contamination." To make good silage clamp contamination must be avoided.
"Trailer wheels and other equipment entering the clamp should be mud and slurry free. When its muddy keep tractors and trailers out of the pit area."
It is also essential to be able to seal the pit effectively to stop air getting in. Mr Adams prefers to see side sheets on the clamp that can be folded in before the top sheet is put on. Ideally, side sheets should reach the floor especially when the pit has sleeper walls.
The pit must be filled quickly with a minimum of 8-10ha (20-25 acres) of grass a day. When less is put in aerobic and clostridial bacteria dominate and cause poor fermentation.
Silage should be rolled as the pit is filled and for less than half an hour in the evening. Excessive rolling is unnecessary.
"Consolidation is not usually a problem except down the sides where it is difficult to get against the wall," he says.
"Dont roll the pit in the morning for it squashes out carbon dioxide and draws in oxygen which can lead to poor fermentation."
Lactic acid fermentation begins after about 20 minutes when no more air is getting in and pH should drop after seven to eight hours. When it takes longer for pH to drop the risk of unwanted bacteria causing poor fermentation is greater, he adds.n
• Cut crop when dry.
• Cut crop 7.5cm (3in) high to leave rubbish.
• Dont rake in soil and slurry.
• Wilt to concentrate sugars but for 24 hours max.
• Fill the pit quickly and evenly.
• Roll for 30 min max in the evening and cover overnight.
• Dont roll in the morning.
• Use the correct additive.
• Seal the clamp quickly.
Fill the pit quickly, with a minimum of 8-10ha (20-25 acres) of grass a day.