Why is soil contamination an issue?

If the silage has an ash content above 10% DM it is a good indicator of soil contamination. Soil is a good source of enterobacteria, clostridia and listeria which increases the risk of a poor fermentation, especially with wetter forages, and can lead to animal health issues.

The risk is highest in wet weather and with lodged crops. If there is a risk of soil contamination, wilt to at least 30% DM and/or use an additive to increase the rate of fermentation.

Minimising soil contamination:

• Fix muddy gateways
• Trap moles and roll the fields before mowing
• Avoid handling the grass in wet weather
• Increase the cutting height
• Avoid running machinery over the cut grass
• Ensure tedders and rakes are set high enough
• Clean clamp machinery, especially wheels, before you start
• Keep the clamp apron clean – don’t allow field machinery and clamp machinery to run over the same area