FARM MANURES 589 



It is evident that poultry excrement is the most valu- 

 able manure produced on the farm. It dries readily 

 and the loss of nitrogen by fermentation is not great. 

 Because of its great strength farmers are very careful 

 regarding its application, as injurious effects on the crop 

 may result. Notwithstanding its great value it probably 

 receives less care than any other manure produced on the 

 farm. 



493. Commercial and agricultural evaluation of 

 manures. For purposes of comparison, experimenta- 

 tion, and sale, farm manures are often evaluated in a way 

 similar to that used with commercial fertilizers. The 

 great difficulty here lies in arriving at prices for the im- 

 portant constituents which are at all comparable with the 

 value of the manure in the field. The following figures 

 are calculated from the preceding tables, and show not 

 only the comparative value of the fresh excrement from 

 different sources but also what might be considered as 

 fair prices a ton for the manures. The value of the nitro- 

 gen is here placed at ten cents a pound, the phosphoric 

 acid at two and one-half cents, and the potash at four 

 cents : 



Value of 



manure 



a ton 



Swine manure $1.50 



Cow manure 1.64 



Horse manure . 1.97 



Sheep manure 2.87 



Poultry manure 4.80 



Average of cow manure and horse manure mixed . 1.80 



Goessman, C. A. Massachusetts State Exp. Sta., Bui. 37, 

 1890, and Bui. 63, 1S96. 



