Covering Silage
Cover silage as the silo is filled. If filling stops for a significant length of time, completely cover the partially filled silo. The plastic cover must be held in place so air cannot enter the silage. A continuous layer of used tires works well for this purpose. If they are not continuous, the plastic may move in the wind and tear. Straw bales or chopped silage may also be spread over the plastic. Another method is to use a fish net or twine mesh to hold the plastic tightly over the silage, or place rows of sand bags every three to six meters (10 to 20 ft.).
Try to plan silo and plastic sheet size to avoid seams. You must seal seams and edges in the plastic cover. You can make a seal with a 45 cm (18 in.) overlap of the plastic sheets set into a groove in the silage surface. Then cover the seam with soil. You can also seal seams using heavy-duty, double-sided tape compatible with the plastic being used. Check with the plastic supplier for suitable products.
Covers should be inspected regularly to repair tears with tape. You must keep the edges of a horizontal silo sealed, since shrinkage leaves a space along the walls. Because silage stacks and most bunkers have a large surface compared to the volume contained, covers are especially important to keep losses low.
The spoiled silage on the surface of a 14 x 28 m (40 x 80 foot) silo is estimated to be worth six times or more than the cost of a plastic cover.
The correct height and width to make a silo depends on daily silage usage based on the removal of a minimum of 10 cm (4 in.) per day from the silage face. Removing less silage leads to spoilage or freezing problems. The silo should be as high as possible to minimize silo width, thereby minimizing surface spoilage. Increased silage height aids in packing. However, silo height is limited by the reach of unloading equipment and wall construction.
A minimum width is 9 m (24 ft.) for front-end loader work. Silo length depends on the total silage needed annually. Some horizontal silo capacities are included in Table 1. Silo capacities are only estimates, as the amount of packing, dry matter content of the material, length of chop and silage material will affect the storage capacity of silage/haylage in all types of storage structures.
Table 1. Estimated Capacity of Horizontal Silos Containing 60-65% M.C. Silage*
| Silage Depth (ft) Average silage density (lb./cu. ft.) |
Silo Width M (feet) |
Silage Remove per 10 cm (4 in.) tonnes |
Silo Capacity (tonnes) ** |
|||
| Per 30 cm (1 ft.) |
Silo Length m (feet) | |||||
| 20(60) | 28(80) | 35(100) | ||||
| 8 32 lb./cu. ft. (density ranges from 30 to 36 lb./cu. ft |
10(30) |
1.15 |
3.45 |
168 |
233 |
297 |
| 12 36 lb./cu. ft. (density ranges from 34 to 38 lb./cu. ft. |
12(36) 17(48) 20(60) |
2.33 3.11 3.88 |
7.0 9.33 11.66 |
335 448 559 |
476 634 792 |
615 820 1026 |
| 16 40 lb./cu. ft. (density ranges from 37 to 42 lb./cu. ft. |
12(36) 17(48) 20(60) |
3.45 4.60 5.76 |
10.36 13.82 17.28 |
456 608 760 |
663 884 1106 |
871 1161 1451 |
* Capacities are dependent on average densities of silage. Silage density increases with increasing moisture content, shorter cut length, packed silage depth and amount of packing.
** Capacity is calculated on the assumption that the far end of the silo is vertical and the front has a two to one slope (i.e., twice as long as the height of silage in the silo).
Source - Silage storage, M.E. Bellman, Silage Seminar'76, Saskatoon, 1976.