GRASS SILAGE 17 



cutting is now possible where formerly it was not. (2) The great reduction in 

 the price of nitrogenous fertilizer has made possible a total seasonal tonnage 

 from such a crop as timothy, which is comparable with average corn yields, and 

 which contains a somewhat higher percentage of protein than either corn or 

 unfertilized grass. 



Phosphoric Acid Silage 



This method of preserving silage has already been referred to and the principle 

 upon which it depends has been explained. (See page 3). Our first experience 

 with it at the State College has been during the present season. Somewhat over 

 100 tons of phosphoric acid silage made from grass were stored last June. The 

 silo was opened the middle of November and at date of writing (January 1939) 

 the material is being compared with corn silage for milk production. Later in 

 the winter it will be compared with molasses grass silage, and results of the trials 

 should be available early in May. 



Details of harvesting and filling are the same as for molasses silage, except 

 that a much smaller amount of phosphoric acid is required. Amounts recom- 

 mended are: 



Per Ion of green crop 



For grass 10 pounds 



For legumes 17 pounds 



These amounts are for commercial acid of 68 percent strength (48.7 degrees 

 Beaume). Acid of greater or less concentration would be required in propor- 

 tionally smaller or larger amounts. 



Although it is possible to add the acid undiluted from the cask, it is now rec- 

 ommended to dilute it at the rate of 1 part of acid to 5 parts of water by volume. 

 The acid is shipped in wooden casks, and although not nearly so corrosive as 

 either sulfuric or muriatic acid, it should be handled in wooden pails and dis- 

 pensed with a wooden spigot such as is used on a cider or vinegar barrel. The 

 cutter and blower should be thoroughly flushed with a hose after the job is fin- 

 ished and between times if there is a lay-ofT longer than overnight. 



Phosphoric acid is easier to regulate than molasses in adjusting flow. It flows 

 more freely and is cleaner. At its present price, it is slightly more expensive than 

 molasses despite the much smaller amount used; but as demand for the particular 

 grade used for silage increases, quantity production maj' bring the price down 

 to a level where it will compete actively with molasses. 



When purchasing phosphoric acid for this purpose, care should be exercised 

 to obtain a grade that contains only very small amounts of fluorine. The element 

 fluorine, when present in any considerable amount in the feed, is injurious to 

 cattle. A large amount of work has been done on this problem and a standard 

 for fluorine has been established. To be acceptable for silage making, phosphoric 

 acid should contain not more than 100 parts of fluorine per million of acid, or 

 expressed on a percentage basis, 0.01 percent. 



Chemical studies of this type of silage as contrasted with molasses silage will 

 not be completed for several months, nor will data as to losses in the silo be 

 available until all the silage has been fed out; but superficial examination in- 

 dicates that the phosphoric acid is as good a preservative as molasses. 



The cattle do not eat the phosphoric acid silage quite as readily as they do 

 the molasses silage. One or two cows consistently refuse from half to all of their 

 daily allowance. Further results than this are not now available. 



