326 PRIXCIPLES OF FEEDING FARM ANIMALS 



Thus, unless the urine is retained either in ii cistern, by a 

 concrete floor with curbing, by plenty of bedding, or unless 

 the animal is on pasture, about half of the fertilizing value 

 of the manure is lost. 



Losses by Leaching and Fermentation. — The loss of the 

 more soluble fertilizing constituents by leaching and fer- 

 mentation is important. The amount washed out by rains 

 may be considerable, especially if the barnyard is not paved 

 or if it is located on the side of a hill. Experiments at the 

 Cornell Experiment Station found that horse manure exposed 

 to the weather from four to six months lost 40 to 60 per cent 

 of its value due to leaching and fermenting. At the Ohio 

 Station it was found that after exposure to the weather for 

 three months steer manure had lost 28 per cent of its nitrogen, 

 14 per cent of its phosphorus, and 58 per cent of its potassium. 

 In this connection Van Slyke,^ makes the following statement : 

 " Taking into consideration both the amount and avail- 

 abiUty of the plant-food leached from stable manure, it is not 

 an exaggeration to say that two-thirds of the plant food 

 value is leached from much of the stable manure used on 

 American farms." 



In addition to losses by leaching, much nitrogen may be 

 lost from stored manure in the form of ammonia or free 

 nitrogen, due to fermentation and decomposition. These 

 losses are especially large if the manure is dry and loose. 

 Thus horse and sheep manures are more liable to losses by 

 fermentation than cow and pig manures, as the latter manures 

 are moister and more compact than the former. In storing 

 manure the farmer can obviate much of the loss due to fer- 

 mentation by keeping the manure moist and compact. Even 



1 "Fertilizers and Crops," p. 306. 



