5 Common Mistakes To Avoid When Making Silage For Biogas

Does your silage have an unpleasant odour? Does your clamp suffer from excessive losses, effluent or mould? Are your biogas yields lower than they should be? If so, you may be guilty of making one or more of the most common mistakes when producing silage for biogas production. Here, Tim Elsome, General Manager of FM BioEnergy, explains how cropfed biogas plants are only as good as the silage put into them – and how you can prevent poor silage from affecting your bottom line.

While the direct costs of poor silage production (such as low dry matter) can be significant, disposing of sub-standard feedstock brings additional financial and time burdens. Yet the alternative option – feeding poor quality silage into your digester – is far worse, potentially causing significant damage and disruption to the resident microbe population. In some cases, it can take many months to repair the damage and get the digester back to a healthy condition, costing the operator thousands of pounds in lost biogas production.

If you experience issues with your silage, you may be making one or more of the following mistakes:

1 Harvesting the crop at the wrong maturity of dry matter

Harvesting maize too soon is one of the most common errors, particularly when trying to balance crop maturity against weather conditions and the ability to harvest it. It is difficult to get good fermentation in maize silage at moisture levels above 70%, and harvesting immature kernels will reduce the starch content of the silage, in turn reducing the amount of food for the bacteria in the digester. Low dry matters will increase the potential for liquid draining from the clamp and could lead to environmental issues with run-off. Conversely, maize silage that is too dry (typically above 36% dry matter) can be difficult to compact.

2 Incorrectly applying additives