Building a silage pit requires careful planning and execution to ensure proper silage preservation and prevent losses. These are all the things you need to consider when undertaking this task:

1. Planning and Site Selection:

Determine Size and Capacity: 

Calculate the required pit size based on the amount of silage you need to store. Consider the number of livestock, feeding rates, and the desired storage period. Consult agricultural resources or experts for accurate calculations.

Choose a Suitable Location: 

Select a well-drained site with easy access for machinery (tractors, forage harvesters, loaders). Avoid low-lying areas prone to waterlogging. The site should also be convenient for feeding out silage.

Consider Orientation: 

Orient the pit to minimise sun exposure, which can lead to heating and spoilage of the silage. Ideally, the long axis should run north-south in the northern hemisphere to minimise afternoon sun exposure.

Soil Testing: 

Conduct soil tests to determine the soil’s bearing capacity and drainage characteristics. This information will help determine the appropriate foundation design.

Environmental Considerations: 

Be aware of local environmental regulations regarding silage storage and runoff management. Implement appropriate measures to prevent pollution of water sources.

2. Design and Engineering:

Pit Type: 

Choose the appropriate pit type based on your needs and resources. Common types include:

• Horizontal (Bunker) Silos: These are the most common type, consisting of a floor and side walls.
• Trench Silos: These are excavated into the ground and may or may not have side walls.
• Tower Silos: These are vertical structures, less common for smaller farms due to higher construction costs.

Wall Design: 

The walls must be strong enough to withstand the lateral pressure of the silage. Common wall materials include:

• Concrete: Poured concrete or concrete blocks are the most common and durable options.
• Steel: Steel walls offer high strength and durability.
• Treated Timber: Can be used for smaller, temporary pits.

Floor Design: 

The floor should be smooth, level, and impermeable to prevent silage juices from seeping into the ground. Concrete is the preferred material.

Drainage System: 

A drainage system is essential to collect and manage silage effluent (juices). This effluent is highly polluting and must be handled responsibly. The system typically includes drainage pipes or channels leading to a collection tank or lagoon.

3. Construction:

Site Preparation: 

Clear the site of vegetation and debris. Level the ground and compact the soil to provide a stable base.

Excavation (if necessary): 

For trench silos, excavate the pit to the desired depth and dimensions.

Foundation Construction: 

Construct a solid foundation for the walls and floor. This usually involves a layer of compacted gravel or crushed stone followed by a concrete slab.

Wall Construction: 

Build the walls using the chosen material. Ensure the walls are plumb (vertical) and properly reinforced. For concrete block walls, seal the joints to prevent leakage.

Floor Construction: 

Pour a concrete floor, ensuring it is smooth, level, and has a slight slope towards the drainage outlet.

Drainage System Installation: 

Install the drainage pipes or channels and connect them to the collection tank or lagoon.

Sealing: 

Seal any joints or cracks in the walls and floor to prevent leakage.

4. Filling and Compaction:

Harvesting the Forage: 

Harvest the forage at the appropriate moisture content for optimal fermentation.

Filling the Pit: 

Fill the pit in layers, spreading the forage evenly and compacting each layer thoroughly. This is crucial for removing air and creating anaerobic conditions. Use heavy machinery like tractors or loaders for compaction.

Monitoring Compaction: 

Monitor the compaction process to ensure adequate density. A well-compacted silage mass will minimise spoilage and improve feed quality.

5. Sealing and Covering:

Covering the Silage:

Once the pit is filled, cover the silage with a heavy-duty plastic sheet to prevent air and water from entering.

Weighing Down the Cover: 

Weigh down the cover with tires, sandbags, or other heavy objects to ensure a tight seal.

Inspecting the Cover: 

Regularly inspect the cover for tears or damage and repair them promptly.

6. Management and Monitoring:

Monitoring Fermentation: 

Monitor the fermentation process by checking the temperature and pH of the silage.

Managing Effluent: 

Regularly empty the effluent collection tank or lagoon and manage the effluent responsibly according to environmental regulations.

Feeding Out: 

When feeding out silage, remove the cover gradually to minimize air exposure and spoilage.

Don’t forget to think of…

• Safety: Prioritize safety during all stages of construction and operation. Use appropriate safety equipment and follow safe work practices.
• Professional Advice: Consult with agricultural engineers or experienced silage producers for advice on pit design, construction, and management.
• Local Regulations: Be aware of and comply with all local building codes and environmental regulations.

Use the best concrete products for silage pits.