Corn harvest puts sustained pressure on people, machinery, and storage. Once the first trailer arrives, there is little time to clear a blocked drain, find a missing sheet or add rolling capacity. Preparing the bunker before harvest reduces these risks.
The aim is to receive the crop safely, pack it evenly, and create an airtight seal as soon as filling is complete. These ten checks cover the main jobs to complete before harvest.
1. Confirm crop volume and available bunker capacity
Estimate the corn tonnage likely to come from the fields assigned to the bunker. Use the cropped area, current yield estimate and the storage density previously achieved on farm to calculate the likely volume. Allow for a safe fill height, wall loading limits and a feed face that can be managed during feed-out.
A bunker with too little capacity may be overfilled, given an unstable profile or left open while extra storage is arranged. If capacity is tight, prepare a second bunker, a suitable area for a drive-over pile, or a revised crop allocation before harvest.
Keep the final profile within the structural design of the bunker. Do not assume that walls, panels or retaining systems can take any load. Obtain competent engineering advice if the loading limits or structural condition are unclear.
2. Remove old silage and contaminated material
Clear the bunker completely. Remove old silage, spoiled material, loose plastic, soil and other debris from the floor, wall edges, and drainage channels. Residue from the previous crop can carry yeasts, molds, and physical contaminants into the new corn.
Use a suitable cleaning method and direct wash water to the correct containment system. Include the approach, tipping area, and machinery in the hygiene plan. Keep tractor and trailer tires free from soil and slurry before they enter the bunker area.
3. Inspect the floor, walls, joints and panels
If using a bunker, Inspect the complete storage structure in good light. Look for and record cracks, damaged joints, eroded concrete, exposed reinforcement, sharp edges and movement in wall panels. Even small defects can damage side sheets or allow air and effluent to pass through once the bunker is under load.
Finish repairs in time for coatings, sealants or concrete products to cure in line with the manufacturer's instructions. Patch tape and other film repair products only address sheet damage. Structural defects need a repair specified by a competent person. Resolve any concern about wall stability before machinery enters the bunker.
4. Test drainage and effluent containment
Clear every drainage channel and test the route to the effluent tank. Check that chambers, pumps, valves and alarms work correctly. Confirm that the tank has enough spare capacity for the expected peak flow. Separate clean water from dirty water wherever the system allows.
In England, the Silage, Slurry and Agricultural Fuel Oil (SSAFO) rules require a silo to have an impermeable base extending beyond the walls, impermeable perimeter channels and a suitable effluent collection system. Different rules may apply elsewhere. Notify the relevant regulator before building a new silo or making substantial alterations where required.
A pre-harvest drainage test provides a clear record. Note the date, result, defects found, and corrective work completed.
5. Define the traffic plan and safe system of work
Plan how forage harvesters, trailers, loading shovels and rolling tractors will move around the site before work starts. Set the entry and exit routes, tipping controls, reversing arrangements, lighting requirements and exclusion zones. Keep pedestrians away from active vehicle routes.
Bunker work carries rollover, edge, and collision risks. The risk assessment should cover machine suitability, operator competence, seat-belt use, side slopes, work near walls and the change between day and night shifts. The bunker manager must be able to slow or stop deliveries when safe packing cannot be maintained.
6. Match packing capacity to the delivery rate
Packing capacity must keep pace with the crop entering the bunker. Silostop's current planning guide for corn silage at around 30% dry matter uses a total rolling weight equal to about 25% of the tons delivered each hour. For example, a delivery rate of 110 tons per hour indicates about 27.5 tons of machinery in continuous operation.
This is a planning guide, not a fixed rule. The capacity required also depends on dry matter, chop length, layer depth, bunker layout, slope, and machinery type. Spread the crop in thin, even layers, usually no deeper than 4 to 6 inches before rolling. Confirm that every machine is suitable for the job and can work within the agreed safety system.
Reduce harvest output if packing capacity and density falls behind. Continuing to deliver silage will trap avoidable air and weaken the preservation process.
7. Order and measure all films before harvest
Measure the bunker or pile footprint rather than copying the previous order. Record internal length and width, wall height, intended final profile and the overhang needed at each edge. Allow enough material for safe installation and a complete seal.
The covering system needs four main components:
· If filling a bunker: Wall Film to line and protect the bunker sides, with enough material to overlap the shoulders.
· An oxygen barrier film placed directly onto the packed corn silage.
· A durable cover to protect the barrier film from UV exposure, animals, and extreme weather.
· A planned weighting system to hold the films in contact with the crop and seal the perimeter.
Silostop Wall Film, Silostop Orange or Silostop Complete oxygen barrier film, and reusable Secure Cover Anti-UV Covers can form part of this system. Select the film size and grade to suit the bunker or pile layout and handling method. Store every roll on a clean, dry surface and protect it from punctures before use.
8. Prepare weights, protection and repair materials
Count the gravel bags, tires, or other suitable weights needed to seal the perimeter and keep the films close to the crop. Inspect reusable covers for wear and repair any serviceable damage before harvest. Clean tires and other weights so they do not transfer contaminated material onto the sheet.
Put patch tape, spare film, safe cutting tools and replacement bags in a clearly marked kit. Keep it where the covering team can reach it without entering an active machinery zone. Arrange bird and rodent controls before sealing, then add cover inspections to the farm's routine checks.
9. Coordinate crop readiness with the bunker team
The expected harvest date and crop dry matter affect bunker planning. AHDB gives 28 to 35% whole-crop dry matter as the general harvest range for corn silage. Drier corn is harder to consolidate, so sufficient packing capacity and controlled layer depth become even more important.
Agree the expected start date, daily output, chop specification and kernel-processing checks with the contractor. AHDB advises a chop length of about 1/2 to 3/4 inch and use of the forage harvester's corn cracker to break the grains. Tell the bunker manager promptly if the crop condition or delivery rate changes.
10. Assign responsibilities and plan the final seal
Assign one person to control the bunker operation. Record who will manage tipping, spread each load, roll continuously, monitor the profile, prepare the films and lead the final covering process. Include relief operators for long shifts.
Decide in advance when final sealing will begin. Position the oxygen barrier film, side sheets, protective cover, weights and repair kit in the order they will be used. Check the weather forecast and arrange enough labor to cover the bunker or pile immediately after final packing.
Fast sealing limits oxygen ingress and supports anaerobic fermentation. Any delay exposes the high-value surface and shoulder areas to avoidable deterioration.
Final corn bunker preparation checklist
· Expected corn tonnage and bunker capacity confirmed.
· Old silage, soil and debris removed.
· Floor, walls, joints and panels inspected; repairs completed.
· Drainage channels tested and effluent capacity confirmed.
· Traffic plan, risk assessment and safe system of work briefed.
· Packing machinery matched to the expected hourly delivery rate.
· Wall film, oxygen barrier film and protective covers measured and available.
· Weights, tape, and spare materials inspected and positioned.
· Contractor, bunker team and crop-readiness information coordinated.
· Final sealing roles, timing and labor agreed.
Prepare early to protect the crop
Corn silage represents a substantial investment in seed, field work, harvesting, and winter feed. Preparing the bunker creates a more controlled route from standing crop to stable storage. It also reduces last-minute decisions during the busiest stage of the process.
Silostop Agri supplies High Oxygen Barrier films, Wall Films, reusable Secure Cover Anti-UV Covers, Gravelbags, and accessories for complete silage covering systems. Check the bunker measurements and material requirements before harvest. Contact the Silostop Agri team if you need support with product selection.