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Thursday March 22, 2018
Why do farmers keep all those old tires?


Nebraska generates almost 2 million scrap car and truck tires a year. Driving through the countryside, it sometimes seems most end up on Nebraska farms. Why does it appear the average farmer never met a worn-out tire he could part with?

In most instances, those piles of tires you see are on livestock farms, in particular livestock farms that raise cattle. Here's the suprising explanation why cattle farmers do that.

Cattle are often fed on a type of feed called silage. Unlike field corn in which the dried ear of corn kernels is picked from the stalk and the stalk then left in the field or baled and removed, silage is the chopped up whole corn stalk along with the ear. Blown into dump trucks at the rate of about 50 tons per city block during harvest, it is hauled back to the farm to be stored for later use.

Because silage is fermented similarly to wine or cheese in order to store without spoiling, it must be protected from the open air. Failing to do so can spoil it quickly, even rendering it virtually useless. One of the world's experts on silage fermentation, professor emeritus of animal sciences at neighboring Kansas State University Keith Bolsen, once noted that if Nebraska farmers harvested an estimated 4.6 million tons of corn silage annually, they probably lose more than three-quarters of a million tons to that kind of spoilage. That loss equates to $1.1 to $1.3 billion a year nationwide.

To prevent that spoilage, in the old days farmers used to store silage upright in air-tight siloes, those familiar round towers you remember standing next to red barns on Old McDonald's farm. But today, the sheer volume of silage large farms need makes that kind of storage for the most part impractical. So large farms have turned to storing silage horizontally, in what are known as bunker or drive-over silos.

And this is where we finally get back to tires. Although silage that has been chopped and piled and packed correctly will seal sufficiently to ferment without losses, it still can be damaged by air and moisture slowly penetrating the top three to four feet. That loss can be cut in half or more by covering the entire pile well by a sheet of black plastic. To hold that plastic down tightly against the surface of the silage, farmers have found nothing works better then old tires, stacked in a single layer shoulder to shoulder across the entire surface.

Although other—prettier—solutions have been proposed, including growing a thin layer of sod on top of the silage or spraying on barrier biofilms that can be incorporated into the feed when the silage is taken out of storage, nothing has been found that works as well, or as cheaply, as tires, which are often split in half to prevent rainwater from accumulating inside. In testament to the fact that someone can always find a business niche, some companies even specialize in providing discarded tires to farmers.

Watch this video as several thousand tons of silage are stacked, packed and wrapped in a frantic, short few harvest days.


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