MANURIAL VALUE OF FEEDING STUFFS 275 



nitrogen and 45.7 per ct. of the ash in the food, storing the balance in 

 its body. (113) Considering the proportion of young animals and of 

 those giving milk on the average farm, it has been estimated 3 that from 

 the feed supplied farm stock about 80 per ct. of the nitrogen, phosphoric 

 acid, and potash is ordinarily recovered in the feces and urine. The 

 proportion of the organic matter of the food which is found in the 

 feces will vary widely, depending on the proportion of difficultly diges- 

 tible roughage in the ration. For well-fed ruminants and horses it 

 ranges from about 20 to 35 per ct. As has been indicated before (432), 

 the organic matter is a highly important factor in the beneficial action 

 of the manure. No definite money value is, however, usually given to it 

 in discussions of the fertilizing value of farm manures. 



434. Influence of feed on the value of manure.- The animal creates 

 nothing of fertilizing value, for it voids only that which it has eaten 

 or drunk. Fart of the fertilizing constituents is retained for the forma- 

 tion of flesh or milk, and the rest is voided in the excrements. The value 

 of manure therefore depends primarily on the character of the food con- 

 sumed. Foods rich in nitrogen, phosphoric acid, and potash yield rich 

 manure; those low in these constituents make poor manure. For ex- 

 ample, in a trial reported by Warington, 4 cows fed alfalfa hay voided 

 daily in their urine over twice as much nitrogen as did cows which were 

 fed only mangels. 



435. Fertility and manurial value of feeds. Since the value of ma- 

 nure depends primarily on the amounts of nitrogen, phosphoric acid, and 

 potash in the feed eaten, it is important to consider the amounts and 

 value of these fertilizing constituents in typical feeds and animal products, 

 as shown in the following table. These are taken from the extensive 

 data in Appendix Table III. The fertility value of each feed per ton, 

 shown in this table, has been computed on the basis of what the total nitro- 

 gen, phosphoric acid and potash in that feed would cost if purchased in 

 commercial fertilizers. The last column gives the manurial value 5 of each 

 feed ; i.e., the value of the manure which would result from feeding 1 ton 

 of the feed to live stock. This has been computed on the assumption that, 

 on the average, farm animals return in the manure about 80 per ct. 

 of the. total fertilizing value of the feed, but that even under good man- 

 agement some losses occur in the nitrogen of the manure which reduce 

 the amount of this constituent in the manure to 65 per ct. of the amount 

 in the feed. Obviously, these manurial values hold good only when the 

 manure is so cared for as to prevent as much as possible the losses 

 mentioned later. Farm manure is relatively rich in nitrogen compared 

 with phosphoric acid. On farms where much live stock is kept and 

 legumes are grown in rotation to help furnish nitrogen, if farm manure 

 only is used as fertilizer many types of soil will become unduly rich in 

 nitrogen compared with phosphoric acid. Under such conditions the full 



3 Van Slyke, Fertilizers and Crops, 1912, p. 300. 



* Chemistry of the Farm, p. 218. Hart, Wis. Bui. 221. 



