Silage bags have become an economical and more convenient method of making silage rather than in the vertical silos that were much more prevalent in years past. The chopped corn is forced into the bag and the tractor, in neutral, moves forward as the bag is filled. The farmer must keep an eye on the amount of silage going into the bag as overfilling it can cause splits. Once the long bag is filled it will be sealed off and fermentation begins.