Various systems exist for storing silage such as bunkers, bales, bale lines, Ag Bags and drive-over piles. Each system has its own advantages and disadvantages, and the appropriate system should be selected for the farm based on flexibility, cost, capacity, space, farm expansion plans and regulatory restrictions.
Drive-over piles are a relatively inexpensive method of producing potentially high-quality silage. The quality of the final silage is dependent on the starting quality of the forage; inoculation; drive-over pile preparation; drive-over pile sizing; construction and compaction; sheeting/sealing and the final feed-out method of the silage.
A small-time investment in preparing to construct the pile will help to ensure high-quality silage. Points to consider include:
- Drive-over piles should be constructed on a clean, hard base allowing hygienic building of the pile
- Space between piles (if more than 1 pile is being produced) to allow for manoeuvring whilst filling and feeding
- Drainage of the site for rain and snow – these must run away from the drive-over pile
- Drainage of effluent – appropriate control of effluent must be in place to meet local environmental regulations. Minimum size of the drive-over pile must be at least 100m away from paths to groundwater such as open water courses and bore holes
- Improvement of the access surface to avoid ruts in the ground and facilitate year-round feeding
- Fencing around the pile to protect from animal damage and wind drifting
Plan & Communicate
- Ensure all employees and contractors are aware of their roles
- Ensure all equipment and consumables are available (inoculant, sheeting, gravel bags)
- Have a contingency plan in place and communicated for weather issues/machinery breakdowns
The drive-over pile should be sized so that a minimum of 15cm are fed out each day during the summer months to stay ahead of aerobic instability.
The following is an adaptation of advice by Roach and Kammel, University of Wisconsin Extension:
- Determine the amount of silage to be fed daily eg 1500Kg
- Divide the weight fed by 720 Kg/m3. 1500Kg divided by 720 Kg/m3 = 2.08m3 of silage removed from the pile
- Define the daily removal rate from the entire face = 15cm
- Divide the volume removed (Step 2) by the removal rate (Step 3). This is the cross section of the pile (surface area).
(Volume/day) ÷ (Daily removal rate) = Area (m2)
(2.08m3) ÷ 0.15 = 13.89 m2
- Assume an average pile depth (for this example 1.5m)
- Divide the cross section (Step 4) by the average depth (Step 5) to obtain the average pile width: 13.89m2 ÷ 1.5m = 9.25m wide
From this example, the drive-over pile will be 9.25m wide and 1.5m high.
The maximum height of the pile should be 2.5m to minimize the risk of the pile slipping during feedout. Initial loads of forage should be spread horizontally across the pile-area base in alternate directions until the desired width of the pile is achieved. Compaction of the pile should be made both horizontally and laterally to gain optimal compaction of the pile without removing the tractor wheels from the forage to maintain optimal hygiene and compaction time on the pile. Once the desired width of the pile has been achieved the pile should be built up from the center with ongoing compaction of the pile during building.
To achieve and maintain appropriate compaction through ensiling and feedout of the silage, the angle of the shoulders of the drive-over pile should be 33° – for every 3m horizontal the shoulder should rise by 1m.
As each area of the pile is completed plastic should be used to cover the section immediately and weighted down. Plastic should be sealed tightly across the surface of the pile, sealing at the edge with either soil, limestone, tires or gravel bags.
The drive-over pile should be split into sections using either tires or gravel bags. If tires are used, they can be split which reduces the number of tires required and facilitates rapid coverage. If whole tires are used they should have holes drilled into them to allow water drainage and reduce the risk of mosquitoes breeding.
Rapid guides (adapted from Drive Over Pile Construction, Roach & Kammel, UofW)
Table 1 – Silage DM needed per day
|No Cows||Kg DM fed/cow/day|
|Wt silage fed/day (Kg)|
Table 2 – Feed volume
|No Cows||Kg DM fed/cow/day|
|Volume Silage Fed/Day (m3)|
Table 3 – Silage pile dimensions
|Kg Silage DM fed/cow/day|
|Width (m)||Equiv No||Maximum Depth of Silage (m)1|
1 Assuming a feedout rate of 15cm per day