The dollars and cents of forage storage

What is the most cost-effective way to store ensiled feeds? When considering storage options for ensiled forages and grains, this question inevitably comes up. Let’s go through some generic comparisons.

First, let’s compare two options to store 2,000 tons of silage:

A 6-inch-thick concrete will be used as the base material and a cost of $4 per square foot will be assumed.

Let’s first calculate the annual cost of Option A.

Borrowed at 6% interest and amortized over 15 years, the annual payment on this investment would be $13,319.

Annually, we will purchase enough Silage Sentinel Red™ oxygen barrier film and conventional black-and-white plastic to cover the silage and have adequate coverage around the edges of the bunker.  Additionally, we will cover both sidewalls with black-and-white plastic only.

Adding in the annual plastic cost of $1,173 gives a total annual cost of $14,492 for 2,000 tons of silage, or $7.25 per ton per year.

Now let’s calculate the cost of Option B.

Borrowed at 6% interest and amortized over 15 years, the annual payment on this investment would be $10,930.

Annually, we will purchase enough Silage Sentinel Red oxygen barrier film and conventional black-and-white plastic to cover the silage and have adequate coverage around the edges of the pile.

Adding in the annual plastic cost of $1,950 gives a total annual cost of $12,881 for 2,000 tons of silage, or $6.44 a ton per year.

Given these assumptions, you can store silage in a drive-over pile (Option B) at a 12.5% discount compared to storing it in a bunker (Option A).

The savings for the drive-over pile remains when comparing a two-unit system, although at a smaller discount. Using the same cost architecture, the cost to store 4,000 tons of silage in two bunkers (Option C) – with two outside walls plus one wall down the middle – is $6.20 per ton annually and $6.09 per ton annually in two 2,000-ton piles (Option D).

That’s a 1.8% discount in favor of the piles, mainly due to the upfront cost of the bunker walls. The cost for the greater concrete footprint and additional tires to cover two piles does begin to negate some of the savings when compared to bunkers.

Now let’s take our individual storage structures and increase their size.

The cost to store 10,000 tons of silage in one 100-by-275-foot bunker (Option E) is $3.43 a ton per year, which is 23% more than the $2.78 a ton per year that it costs to store 10,000 tons of silage in one large drive-over pile (Option F).

Finally, comparing two adjacent, large storage structures yields the lowest costs. The cost to store 20,000 tons of silage in two 10,000-ton bunkers (Option G) is $3.07 per ton annually, 14% more than the $2.69 per ton annually that it would cost for two 10,000-ton piles (Option H).

If cost were the only factor in picking a storage structure, piles would be the obvious choice. The upfront cost of bunker walls may be inhibitory in many situations. The annual cost per ton of forage stored in piles only grows with the addition of more tons.

However, there are other factors to consider outside of cost. In many areas, space is a limiting factor. Bunker walls allow for a more compact form of storage taking greater advantage of vertical space than piles. If adequate space is available, a cement pad provides flexibility in forage pile dimensions, alignment and overall size. The greatest drawback of piles is the additional space and concrete that may be needed to account for their greater footprint. Reach out to your Vita Plus forage consultant for more information on forage storage options.