SILAGE 



287 



or of clay tiles or blocks. The important points are that 

 the walls be air-tight, and smooth on the inside, and, in 

 cold climates, that they keep the silage from freezing 

 unduly. The inside surface of the wall must be smooth, 

 and free from needless corners, so that the silage can 

 be packed without leaving air spaces in it. A layer of 

 the silage at the top will spoil, from air contact, unless 

 the farmer begins to use 

 it as soon as it is stored J ; 

 and, after use begins, 

 about two inches of 

 depth must be fed each 

 day, to prevent too long 

 a contact of any part 

 with air. 



The principle of silage 

 making, then, is that of 

 " canning " the green 

 forage with all its juices 

 in it. The bacteria al- 

 ready in the substance, 

 however, are not killed 

 by heat, as in most canning of vegetables. 2 Sourness or 

 acidity is produced by cellular respiration which continues 

 until all the free oxygen is exhausted. The acids so pro- 

 duced protect the ensilage from harmful bacteria. The 

 sourness is neither objectionable to cattle nor harmful to 

 them. If air reaches the silage, however, so that molds 

 form, it is unfit for any animal, and sometimes fatal to 

 horses. 



Cow PEAS. 

 Natural size. 



1 This spoiled top layer a foot or so in depth will protect the silage be- 

 low for a long time. Sometimes, too, if the silage is not to be used for some 

 months, the farmer wets the top and sows oats or barley upon it. The thick 

 green growth that results effectually " seals " the silo top. 



2 Some vegetables, like rhubarb, can be canned without heat. 



