SIXTH ANNUAL YEAR BOOK— PART VIII. 



THE CONSTRUCTION OF SILOS. 



Wjlber J. Fraser, Chief in Dairy Husbandry, University of Illinois, in 

 Experiment Station Bulletin, No. 102. 



INTRODUCTION. 



There has been much discussion through the agricultural press and 

 at farmers' institutes concerning the importance of the silo and the 

 advantages and disadvantages of the different styles of construction. 

 As yet, however, comparatively few dairymen and stock raisers of 

 Illinois fully appreciate the value of silage, and as there are not one- 

 tenth as many silos in the state as the economy of silage as a feed, 

 especially for dairy cows, would warrant, the Experiment Station has 

 deemed it wise to issue two bulletins on this subject. 



Bulletin No. 101, discusses the subject of crops for the silo and cost 

 of filling. The aim of this bulletin is to direct attention to some of the 

 essential points in silo construction and also to show the serious defects 

 in some styles of silos, both in the material used and in the manner of 

 construction. Cheap silos which are poorly built have done much to 

 injure the cause of silage, for since they do not preserve their contents 

 perfectly there is necessarily great loss. The problem is, therefore, to 

 build an enduring, air-tight, rigid structure at least expense. 



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ESSENTIALS OF A SILO. 



There are several points that must be closely observed in making 

 silage if it is to be well preserved, and the neglect of any one of these 

 will make, in the final result, the difference between success and failure. 

 These essentials are close packing, when the crop is at the proper stage 

 of maturity, in an air-tight structure having perfectly rigid walls. 



The stage of maturity and method of packing were treated in Bulle- 

 tin No. 101. Of equal if not greater importance, is the proper construc- 

 tion of the silo. If the sides of the silo are not air-tight, the air which 

 passes through will cause the silage to spoil, and if the walls are not 

 perfectly rigid, the pressure of the silage will cause them to spring out, 

 allowing the air to enter between the silage and the wall. In either 

 case the result will be the same — decayed silage. 



The outward pressure on the wall of a silo filled with cut corn is 

 about 11 pounds for every foot in depth; making a pressure of 110 

 pounds at a depth of 10 feet; 330 pounds at a depth of 30 feet; and the 

 enormous pressure of 440 pounds per square foot at a depth of forty 

 feet. This increase in pressure as the depth increases must be considered 

 in silo construction and the lower portion made much the stronger. 



Before building a silo the most careful attention should be given to 

 location, size, form, and method of construction. These will differ some- 

 what according to locality and individual needs. A brief discussion of 

 these questions follows: 



