6 
The Colorado Experiment Station. 
tight. It is a proven fact that air-tight walls can be constructed 
from a variety of materials. The water of the green feed or added 
water aids in this exclusion of air, so that the walls should be so 
constructed as to make them not only air tight but also water-tight. 
If the walls absorb large quantities of moisture, they draw out mois¬ 
ture from the silage and allow mold to develop around the walls. 
Durability .—The material used for silo walls should not only 
be of a character which will insure efficiency in silage keeping, but 
should also be of a durable nature. The silo is rather expensive in 
any material, so that the material which will last over the longest 
period of years and give satisfaction will be cheapest in the end, 
even though the first cost will be slightly greater. A silo which is 
weather, storm and fireproof is a great asset, as farm buildings as 
a rule are not generally insured heavily, if at all, and the risk of loss 
is great, due to lack of fire protection. Such a structure, with noth¬ 
ing about it to decay and need replacement after a few year’s use, 
will require much less care and attention, which would add much to 
the satisfaction, and decrease expenses of the owner. A permanent 
structure of any kind is a good indication of the judgment and fore¬ 
sight of a business farmer. 
Cost .—The silo which will give the most and best service for 
the least money is, of course, the kind to buy. First cost is, how¬ 
ever, only one of the factors to be considered. Cost of upkeep and 
period of usefulness should also be figured on. It is therefore pos¬ 
sible that some types of silos, although their first cost may be great¬ 
er, are really a better investment, if their annual cost of upkeep is 
small and their period of usefulness, due to' durable material used, 
extends over a long period of years. Upkeep is quite a factor when 
we stop to consider that the silo is generally empty during the most 
trying season, and when labor is scarce due to urgent farm work. 
It is work that is too often put off or forgotten. Such neglect proves 
expensive with silos, which demand attention. 
Convenience .—The above ground types of silos are generally 
considered more convenient than the below ground types. It is 
easier to throw silage down than to throw or elevate it up. The 
continuous door is also more convenient than the intermittent, since 
the opening is always nearer the level of the silage and therefore re¬ 
quires less pitching up over the door. It is not desirable with above 
ground silos to go more than 5 feet below ground or to exceed 18 
to 20 feet in diameter for convenience sake. 
Attractiveness .—Any properly constructed silo adds to' the at¬ 
tractiveness of the farm and enhances its value. Like other farm 
