Thirty-fourth Annual Convention. 215 



age is exposed to the air, the silo should not be of too great 

 diameter. Not more than eight square feet of surface should be 

 allowed for each cow in winter, then, when feeding 40 pounds of 

 silage per cow, a layer about 1^ inches deep would be fed off 

 daily. When silage is fed in summer it is advisable that the ex- 

 posed area be not over half this size, so that a layer three inches 

 deep may be used daily. However much stock is to be fed, a silo 

 20 to 32 feet in diameter is as large as should be built. If a silo 

 is of greater diameter than this, much of the silage is at too great 

 distance from the door, increasing the labor of removal. 



The deeper the silo the greater the pressure and the more 

 compactly will the silage be pressed together, hence the larger the 

 amount that can be stored per cubic foot. For example, a silo 

 20 feet in diameter and 40 feet deep will hold twice as much as 

 one of the same diameter and 25 feet deep. This shows the 

 economy of reasonably deep silos. To be well proportioned the 

 height should not be more than twice the diameter. No silo 

 should be less than 30 feet deep, and to get sufficient depth for a 

 silo not over 12 feet in diameter, it may be placed 4 or 5 feet into 

 the ground. 



The number of tons of silage needed can readily be esti- 

 mated from the size of the herd and the amount to be fed daily. 

 Even when it is desired to feed as much silage as possible not 

 more than 40 pounds per cow should be fed daily. In Illinois, 

 silage will usually be needed from about October 20 to May 10, 

 or 200 days. Each cow should have an allowance then of 200 

 times 40 pounds, which is 8,000 pounds of silage, or four tons 

 per cow for the year. A herd of ten cows will require a silo hold- 

 ing 40 tons ; a herd of 30 cows 120 tons ; 50 cows 200 tons ; and 

 100 cows 400 tons. Where young stock is raised an allowance 

 should be made for them. From the amount of silage needed the 

 dimensions of a silo of the required capacity may be determined 

 from Table 1, which gives the capacity in tons of silos of differ- 

 ent diameters and depths. . These estimates apply to silos filled 

 with well matured corn that has been allowed to settle forty- 

 eight hours and then refilled. It is evident that to get this rated 

 capacity a silo which had been filled rapidly must be refilled after 

 settling forty-eight hours. 



