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