Aug. 6,1917 Chemical Studies in Making Alfalfa Silage 291 



time, the maximum was larger. This was not due to transfer of acid 

 from above, as the acidity of the silage in the cans was in all cases very 

 nearly the same as the maximum, and in some cases larger. 



One function of the acid in silage is to furnish an environment unfavor- 

 able to putrefactive organisms. If easily fermentable carbohydrates 

 such as are found in molasses or sweet-sorghum butts are present, the 

 needed amount of acid will be developed through the action of bene- 

 ficial organisms. The starch in com is changed more slowly. In alfalfa 

 alone the total amount of acidity produced is too small to bring about 

 the desired condition. Furthermore, silos are not perfectly air-tight, 

 like the bottles used in the preliminary work. Entrance of air makes it 

 possible for putrefactive bacteria to grow. 



Sugar content. — Sugar was determined in the same alcoholic extract as 

 was used in the acidity determination. The percentage of sugar varies 

 among the different samples obtained from the same silo, but they all 

 have this in common : In a few days to four weeks the sugar disappears. 

 In com, rye, and sweet-sorghum butts the sugar disappears in the shortest 

 time. This must mean that the soluble carbohydrates are at once used 

 in the production of acid. Where molasses was used in the largest 

 amount, the sugar lasted the longest. More molasses than needed was 

 used. In alfalfa alone the sugar also lasted long. This would appear 

 to indicate that the conditions for transforming the carbohydrates in 

 alfalfa into acids were not favorable. 



Volatile acids. — Volatile acids were determined according to the 

 method of Dox and Neidig.^ While the total acidity was calculated as 

 lactic, the volatile acidity was calculated as acetic. By omitting the 

 results for the first few days the following calculated averages were 

 obtained for the total and volatile acidity: 



Total Volatile 



silage. acidity. acidity. 



Alfalfa alone i. 483 i. 038 



Alfalfa -f- molasses, 20:1 ' 2. 413 . 958 



Alfalfa -f- molasses, 10:1 3.009 i. 119 



Alfalfai-f- com chop, 10:1 2. 242 i. 229 



Alfalfa -|- sweet-sorghum butts, 6:1 i. 856 i. 126 



Alfalfa -f rye, 2:1 1-975 -750 



Rye alone i. 917 . 569 



Alfalfa alone produced the largest relative amount of volatile acidity. 

 Rye produced a low amount. In the best silage the relative amount of 

 volatile acid was about one-half of the percentage of total. The volatile 

 acidity increased, but the rate of increase was not regular, nor does it 

 seem to have any definite relation to changes in total acidity.^ 



* Dox, A. "W., and Neidig, R. E. THE VOLATILE aliphatic aods ot CORN SILAGE. lowa Agr. 

 Exp. Sta. Research Bui. 7, 32 p. 1912. 



' The cause for the relatively large figure for volatile acidity in alfalfa alone will be explained in the fuller 

 report to be published. 



100302°— 17 2 



