100 AGRICULTURE. 



to the soil a large per cent, of the important 

 food elements taken up from the soil by the 

 plants will be restored to the soil. For it must 

 be remembered that this compost not only con- 

 tains the indigestible food elements, but also the 

 broken-down or worn out animal tissues. 



(i) VALUE IN FURNISHING PLANT-FOOD. 

 The amount and kind of the elements of plant- 

 food found in stable compost depend upon the 

 kind of food * fed to stock, and the age and 

 kind of stock to which it is fed, and the care 

 taken of the compost. Mature animals (except 

 milch cows) return, sooner or later, nearly all of 

 the fertilizing f elements of the food in the 

 waste discharged, while only one-half or two- 

 thirds is returned by young and rapidly growing 

 animals. Fattening cattle return from 85 to 90 

 per cent. 



Roberts estimates the commercial value of 

 the fertilizing materials found in the compost of 

 different farm animals as varying from $2.43 to 

 $4.25 per ton, rating the nitrogen contained at 

 15 cents, phosphoric acid at 7^ cents, and potash 

 at 42 cents per pound. He also states that in 

 many cases the " computed value of the waste 

 is nearly one-half the cost of the food " ; but 

 adds, " this value can seldom be realized when 



* See Table, p. 134. 



f Henry's Feeds and Feeding, p. 270. 



