THE FERMENTATION OF SILAGE 85 



belt from 1885-1895 show an acre cost of $6 to $8 and a bushel cost 

 of about 20 cents. From 1895 to 1905 various records show the 

 acre cost to be $10 to $14, and bushel cost from 24 to 30 cents. In. 

 the eastern States the cost has always been much higher than this, 

 ranging from 40 to 50 cents per bushel. 



Data collected by the U. S. Department of Agriculture for the 

 year 1909, show an average cost for the United States of 37.9 cents 

 per bushel, while for Illinois and Iowa, the two leading corn States, 

 the bushel cost was 31 and 30 cents, respectively. 



How Silage is Made. Vegetable matter is caused to decay 

 through the presence of bacteria or molds. Two methods are used 

 to preserve materials, (1) by drying, as moisture is necessary for 

 growth of bacteria or molds, (2) by heating to destroy organisms 

 or some preservative to retard the growth of organisms. 



The following statement from Iowa Bulletin 168 gives a concise 

 statement regarding the fermentation and preservation of corn 

 silage. 



" THE FERMENTATION OF SILAGE 



" Certain other well-known fermentative processes are somewhat 

 similar to silage fermentation. When hay is stored too green it is 

 likely to heat, even to the combustion point. This heat is only the 

 outward evidence of other changes which are taking place in the 

 hay. Grain stored in bins undergoes certain chemical changes, 

 which sometimes develop a noticeable amount of heat. These and 

 similar changes which are undergone by all living plant material 

 when stored in large masses, are in some respects like silage fer- 

 mentation. The fermentation of sauer kraut is also similar in that 

 the preservation of the kraut depends upon the formation of organic 

 acids by bacterial action. The formation of vinegar from cider 

 involves the production of acetic acid, which is one of the acids found 

 in silage. This change takes place necessarily in the presence of air. 

 On the contrary, the changes which are normal to the formation of 

 good silage take place almost entirely in the absence of air. 



" In silage making the chopped corn forage is tightly packed into 

 an air-tight silo, with plenty of moisture present, and fermentation 

 begins at once. The first evidences of change are a slight rise 

 in temperature and the evolution of carbonic acid gas. The tem- 

 perature of the silage rarely exceeds 85 to 90 Fahrenheit, except 



