Silage mist could prove a killer

AS SILAGING gets into full swing farmers have been warned about the severe, and possibly fatal, consequences of inhaling gases produced by fermentation.

Scientists at the Institute of Grassland and Environmental Research at Aberystwyth say silage makers are often unaware that the mist seen around clamps a few days after filling can be lethal.

“During the first few hours of silage fermentation undesirable bacteria such as Eneterobacteria, which are present on the grass, transform excess nitrate collected within the leaves of grasses to nitric oxide and nitrous oxide, which can form a mist,” said Dr David Davies.

The gas is highly toxic and inhalation can lead to the condition known as silo-fillers disease, which causes severe respiratory problems.

In contact with water the gases form nitric acid capable of turning the ensiled grass orange and of burning human skin.

The first two days of fermentation are critical because the undesirable bacteria are killed as the silage becomes more acidic.

Dr Davies advised farmers to make sure that enough nitrogenous fertiliser is applied to optimise grass growth without creating a surplus in the leaves.

If there is a doubt pre-cutting analysis will show whether nitrates have been utilised.

He warned that wet weather followed by a few dry days prior to harvesting can increase the risk of residual nitrate in grass.

Good compaction reduces the amount of air in the silage, which increases fermentation speed and the creation of acidic conditions.

“If you see a mist, or material round the edge of the clamp is coloured orange then leave well alone, and keep all livestock away. The silage should be fine but you may not.”


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