SILOS, THEIR CONSTRUCTION AND USES. 



809 



made under the directions of the experiment- 

 station, and in the most approved manner, the 

 results show at least the average loss resulting 

 from the preservation of green food in silos 

 made by a simple excavation in dry earth. 

 While the losses are large, there is always a 

 counterbalancing effect in them. The loss in 

 non-nitrogenous food- elements, which are in 

 excess in fodder-corn and most other matters 

 commonly preserved in silos, is much greater 

 than in the nitrogenous or flesh-producing 

 elements. The loss in the former is over 50 

 per cent; in the latter seldom over 25 per 

 cent; so that ensilage from such silos usually 

 furnishes a better - balanced ration than the 

 green food. But tbe waste is too great to 

 make it economical to preserve anything in 

 earth-pits which could be preserved by desic- 

 cation. 



Fully appreciating that access of air to the 

 ensilage was the cause of its wasting, M. Au- 

 guste Goffart, of France, introduced improve- 

 ments in silos for excluding air. An excava- 

 tion was made with perpendicular sides, and 

 protected with walls of masonry, either brick 

 or stone, with sides and bottom water-tight. 

 When the material to be preserved had been 

 snugly packed in the silo, the whole was cov- 



Fio. 1. CROSS-SECTION or A BARN AND SILO. 



ered with strong planks, closely fitted, to ex- 

 clude air, and laid directly upon the contents 

 of the silo, and then heavily weighted with 

 stones. By this means the ensilage was pressed 

 into the most compact form, and the air in the 

 vacant spaces forced out, the cover following 

 down as the contents of the silo settled, the 

 closely fitting cover protecting against the ad- 

 mission of outside air. Thus protected, the 

 loss was reduced to a minimum, and the utility 

 of silos greatly enhanced. Since the introduc- 

 tion of this improvement, earth-pits have been 

 steadily going out of use, and air-tight silos 

 multiplying. In the United States silos having 

 tight walls, with rare exceptions, are only used. 



Different materials and a variety of modes of 

 construction are employed. Some are made 

 with thick walls of solid masonry; others laid 

 up dry, and pointed inside and out ; some are 

 made of brick or wood, but more are probably 

 made of concrete than any other material. It 

 has special advantages for the purpose. It 

 makes an air-tight wall ; is durable, not being 

 affected by frost or water ; is a poor conductor 

 of heat, is cheap, and readily constructed with- 

 out skilled labor. 



Silos are preferably located at the side of 

 the barn in which their contents are to be 

 fed, the bottom being on a level with the 

 bottom of the stable, for convenience in 

 feeding, as in Fig. 1, a door opening from 

 the bottom of the silo, or each of its compart- 

 ments, to the stable, for conveying food to 

 the stock. The necessary covering for pro- 

 tection against wet is easily made in such a 

 location. 



Deep silos preserve their contents best, and 

 are more economical in covering and in weights 

 than shallow ones. Twenty feet is a desirable 

 depth when it can he obtained, and an inclined 

 surface gives the best facilities for regulating 

 depth, and the greatest convenience in filling. 

 The lower the temperature the greater the re- 

 sistance to change. It is therefore de- 

 sirable that when the contents of the 

 silo have settled all they will, they 

 should not rise above the surface of 

 the ground. So much of the top of 

 the silo as will be vacant when the 

 settling is done, may as well be above 

 the surface of the ground, and consist 

 of a curb of wood that can be removed 

 and replaced at pleasure. In the con- 

 struction of silos it is a matter of great 

 importance to have the opposite sides 

 exactly parallel, and the surfaces as 

 smooth as possible, so that the cover- 

 ing in settling shall neither crowd, to 

 prevent going down without obstruc- 

 tion, nor leave cracks for air to work 

 in. For the same reason it is also im- 

 portant that the walls should be so 

 thick and firm as not to spring, either 

 in or out. Space is best economized 

 by building as nearly square as con- 

 venience will allow, since the same 

 surface of wall in a square form will in- 

 close more space than in a parallelogram ; 

 and experience has proved that it is bet- 

 ter to divide a silo into compartments by 

 partitions, sixteen feet apart, rather than to 

 have all the space in one room so large as 

 to make the covering unwieldy, and to cause 

 a needlessly large surface to be exposed to 

 the air when feeding. A silo divided, as in 

 Fig. 2, will require forty-four feet less length 

 of wall, and expose but one third the amount 

 of surface when feeding, as when arranged 

 as in Fig. 3. By filling one apartment at a 

 time, injury will be avoided by keeping open 

 too long. 



