374 



THE PRINCIPLES OF SOIL MANAGEMENT 



the more of them the manure will contain. A highly 

 carbonaceous ration produces a poor manure largely 

 because it is low in nitrogen. The manurial value of a 

 food-stuff is generally increased by passing through the 

 animal, provided it can largely be recovered, because 

 the digestion process leaves it in a condition more favor- 

 able to decomposition and to thorough mixing with the 

 soil. 



247. Use of the animal. The amounts of the ferti- 

 lizing constituents recovered in the excrement vary to 

 some extent with the use that is being made of the ani- 

 mal. Animals that are being fattened, or that are pro- 

 ducing milk, divert a portion of the fertilizing constit- 

 uents to their products. Experiments by Laws and Gil- 

 bert with different classes of animals used for different 

 purposes show the following disposition of some of the 

 constituents of the food. As the excrements include 

 the perspiration, the small amount of matter passing 

 off in that form is, of course, not recovered in the manure. 



Table LVI 



