In less-than-ideal harvest conditions, producers may be forced to ensile forages at high-moisture content. Early harvests — with moisture levels higher than 70% — can lead to increased effluent runoff.
Also called seepage, it is the liquid squeezed out of forage after it is packed in an ensiling structure. Silage effluent is a high-nutrient liquid waste product with a high biological-oxygen demand (BOD), similar to liquid slurry. Effluent will no longer be produced once forage reaches about 32% dry matter (DM) in silage bunkers or drive-over piles.
If not properly drained, effluent adversely effects the fermentation of forage and can encourage the formation of undesirable acids and ammonia.
Typically, effluent has a pH between 3.5 and 5.0, making it highly corrosive to both metal and concrete and capable of damaging the silage storage structure. In addition, effluent run-off can cause environmental damage.
Excess effluent production can be prevented by:
- Harvesting at a sufficiently high DM
- Increasing the length of the forage chop at ensiling
- Reducing the level of compaction of the forage
- Including layers of adsorbent material, such as straw
- Covering horizontal silos to reduce the prolonged flow of effluent
Effluent production can also be managed when designing a bunker or drive-over pile by:
- Locating silage-storage structures away from open waterways and wells
- Preparing the ensiling site to divert water and effluent from the silage and toward a common collection and treatment point
- Installing an effluent collector at the silo entrance to help control effluent run-off
Silage effluent also can be captured, diluted and used as a fertilizer but should be carefully managed — especially if mixed with slurry due to the potential production of hazardous gases, such as hydrogen sulfide.
More information about properly storing silage can be found at www.qualitysilage.com.