110 SILOS OTHER THAN WOOD. 



.saving effected in filling, but this hardly holds true, as with 

 modern machinery it is little more expensive to fill a silo above 

 ground than one below the surface. 



The failure of the silage to thoroughly pack by its own weight 

 is one of the principle draw-backs to the pit silo. This is on ac- 

 count of the lack of depth so much in evidence in structures of 

 this kind. 



Another objection to the silo is that poisonous gases are likely 

 to accumulate in the bottom and render the silo dangerous to en- 

 ter. Lowering a light would soon discover the presence of such 

 carbon dioxide gas which if present would immediately put the 

 light out. These gases are heavier than air and the air would 

 have to be agitated to dispel them since there is no air drainage 

 in an underground silo. 



Again, unless the soil is dry and very hard or has excellent 

 drainage there would be the danger of water seeping into the 

 hole and thus spoiling the silage. The likelihood of caving in 

 either while building or after the first silage crop was taken out 

 would also have to be overcome. 



Some of the essentials in building underground silos aside 

 from firm dry soil are that they should have a curb or collar ex- 

 tending from below frost line to a few inches above ground; that 

 they should be plastered from % to 2 or 3 inches thick and washed 

 with a cement coat to make them water- and air-tight, the walls 

 being sprinkled lightly before plastering, if dry; that the walls 

 should be smooth and perpendicular for even, solid settling; that 

 a cover should be provided as a protection against children, ani- 

 mals or foreign matter and to insure free air circulation. 



