SCIENCE AND PRACTICE OF FEEDING 67 



elements are various animal manures, refuse 

 from the carcasses of animals, and various 

 mineral substances. Animal manures all 

 contain more or less of each of the three 

 elements needed, and the urine more of them 

 than the solid matter. Manure from horses, 

 cows, oxen, or sheep is the most desirable, 

 that from sheep containing more than three 

 times as much nitrogen as that from cows, 

 while that from horses contains, when fresh, 

 about twice as much. Cow manure is 

 always preferable to horse manure, how- 

 ever, because of its ability to retain the 

 fertilizing elements longer. Sheep manure, 

 if properly cared for, is better than cow ma- 

 nure, but less of it should be used, propor- 

 tionately. Ground bone or bone meal that 

 has been properly prepared is one of the 

 best and safest sources of plant food. This 

 contains a large amount of phosphoric 

 acid, considerable nitrogen, and lime. Dried 

 blood and tankage supply nitrogen, as do 

 also nitrate of soda and sulphate of ammonia. 

 Nitrate of soda contains nitrogen in the most 

 available form of all the sources of supply. 

 Nitrate of potash is a good but expensive 

 source of supply for potash. Wood ashes, 



