424 IOWA DEPARTMENT OF AGRICULTURE 



FROST RESISTANCE. 



Owing to the fact that all Iowa silos do not now have roofs and that no 

 two men use the same methods in feeding silage, it has been difficult 

 for the authors to compare the frost resistance of different types of silos. 

 It is, however, a very conservative statement to say that the average 

 amount of frozen silage found in Iowa silos during personal inspection 

 trips did not exceed the amount found in wooden silos in the same neigh- 

 borhood and under the same conditions of exposure. 



The hollow wall of the Iowa silo in which the circulation of air is quite 

 thoroughly restricted, tends to make it frost resistant. Dry fir lumber 

 is about six times as efficient a non-conductor of heat as vitrified clay. 

 Since the Iowa silo wall is twice as thick as the average silo stave, and 

 because it is only about one-fourth solid, it should be at least equally as 

 efficient as a two-inch wooden wall which is always moist, a condition 

 which lowers the efficiency of wood as a non-conductor. The Iowa silo wall, 

 however, is not nearly as frost proof as a double wall concrete silo or a 

 cement block silo with less material joining the two walls and with re- 

 stricted air circulation. 



COXVEXIEXCE. 



The Iowa silo has been designed and constructed with either individual 

 or continuous doors. The continuous doorway has crossties 42 inches 

 apart which is an important advantage over the usual construction which 

 in some instances has hoops or ties as close as 26 inches. When crossties 

 are close, the continuous door offers but little advantage if any over the 

 individual door. With these improved doors, the Iowa silo offers as many 

 advantages for convenience in removing silage as any construction now 

 known. Fig. 5 is a view of the continuous doorway of the Iowa silo, look- 

 ing toward the roof, showing the large openings between the crossties. 



The concrete roof of the Iowa silo has a wide, flat gutter in which it is 

 possible to stand while adjusting the blower pipe of an ensilage cutter to 

 the silo for filling. This is a valuable convenience compared with the 

 usual steep roof upon which it is impossible to stand, requiring that the 

 work of adjusting the blower pipe be done from the window or a ladder. 



PORTABILITY. 



In no sense can the Iowa silo be considered portable. If a silo is desired 

 which must be moved to a new location after a few years, it is doubtful if 

 the Iowa silo would fill the requirements. The roof and door frame would 

 be entirely destroyed in moving and it would be worth nearly as much as 

 the value of the blocks to clean them for use the second time. 



FIRE PROOF QUALITIES. 



The Iowa silo is perfectly fire-proof. It is hard to see how it could be 

 even slightly damaged by a fire. In general, fire-proof construction is given 

 too little attention. One of the authors of this bulletin visited a masonry 

 silo from which silage was fed within twenty-four hours after all the 



