12 SILOS: CONSTRUCTION AND SERVICE 



with on account of heat passing out through the wall; and 

 since heat is one of the factors in checking fermentation, 

 there are different conditions and results at the wall than 

 in the center. This is noticeable in any kind of silo. In 

 silage taken from against the wall, a slight difference in odor 

 can always be detected, no matter how good and tight the 

 walls are. This does not mean that the silage at the wall 

 is materially inferior to that elsewhere, nor does it mean that 

 just because there is a little difference in the odor the silage 

 is all bad. The writer has never found a silo in which this 

 difference could not be detected. 



With a rise in temperature, any material is certain to 

 expand. The silage settles very rapidly the first few days, 

 and this, together with the rise of temperature, is the main 

 source of the outward pressure; during the first few days 

 after the silo is filled it is greater than at any other time. 



The growth of mold or the decay of the silage can only 

 occur when air is admitted. If the silage is at all dry and 

 air is admitted mold results. If, however, the moisture 

 content runs as high as 65 to 70 per cent, and air enters, the 

 result is usually rotten silage. It is important to mention 

 this, as the rotten silage prevents air from reaching the rest 

 of the silage, so the loss in this case is usually not very great. 

 In the case of dry silage, however, the admission of air causes 

 a growth of mold which does not prevent to so great an extent 

 the entrance of air. 



The growth of mold does not effectively prevent air from 

 reaching adjoining silage. Therefore the loss is often much 

 more serious than would have been the case with more mois- 

 ture in the silage. In some cases concrete silos could more 

 appropriately be called gravel silos, as they allow the air to 

 filter through and at the same time absorb moisture from the 

 silage, making the conditions right for the development of 



