282 PRINCIPLES OF AGRICULTURAL CHEMISTRY 



The Mississippi Experiment Station determined income and 

 outgo of plant food, and found that young fattening steers excrete 

 on an average 84 per cent, of the nitrogen, 92 per cent, of the 

 potash, and 86 per cent, of the phosphoric acid of the food con- 

 sumed. 



Differences in the composition of manure from differ- 

 ent animals are due in part to difference in the food eaten by the 

 animal, and in part to the water-content of the manure. Animals, 

 such as hogs, which feed on concentrated foods, produce a 

 stronger manure than those which require more bulky food, such 

 as horses and cows. 



Sheep manure is a rich manure containing only a small amount 

 of water. It ferments more rapidly than cow manure, but not 

 as readily as horse manure. It is concentrated and valuable for 

 gardening purposes. 



Horse manure is dry, undergoes fermentation rapidly, and gen- 

 erates a high heat on account of its loose texture. In the pro- 

 cess of fermentation the nitrogen is converted into ammonium 

 carbonate, which, being volatile, is liable to be lost. A well fed 

 horse at ordinary hard work will produce about 50 pounds of 

 solid and liquid excrement per day. 



Hog manure is very variable in composition. It contains much 

 water, ferments slowly, and generates little heat in fermentation. 



Coiv manure is poorer than hog manure, decomposes slowly 

 and generates little heat. A milch cow will excrete daily about 20 

 to 30 pounds liquid and 40 to 50 pounds solid excrement per day. 



Poultry manure is rich in nitrogen. It ferments rapidly and 

 easily loses nitrogen. In order to prevent loss from volatilization 

 as ammonia, some preservative should be added to it. 



Quality and Quantity of Feed. Since manure can contain only 

 the fertilizing constituents of the food, the composition of 

 manure depends largely on the composition and amount of the 

 food. If the food is poor in nitrogen, phosphoric acid, and 

 potash, the manure will also be poor. The richest manure will 

 be obtained when concentrated materials rich in nitrogen are fed, 

 such as cottonseed meal, gluten meal, bran, clover hay, etc. Since 



