There would be much less spoilage and waste of silage if the more than 22,000 farmers in Iowa who put up this valuable feed understood just what happens in the fermentation process, instead of following directions in “cook book” style. There would also be more use of other crops than corn for silage, especially in cases of emergency, if the merits of some of them for this purpose were known. Conditions are not always normal and favorable for the best results in making silage, and a knowledge of the principles upon which the proper preservation of silage depends is of considerable value when conditions are unusual. A great deal of uncertainty about silage fermentation still exists. This is evidenced by the number of samples of moldy silage sent in to the Iowa Agricultural Experiment Station and by the incorrect ideas regarding the fermentation that are still current.