132 The Potato 



its phosphoric acid, the element needed to balance the 

 manure as a potato fertilizer. Acid phosphate is valu- 

 able for this purpose, but it must not be used under the 

 feet of animals. Manure spread in the winter suffers no 

 loss from heating and but little from leaching unless the 

 field is so sloping that water runs off rapidly. It is so 

 difficult to prevent loss in manure kept in other ways 

 that spreading as rapidly as made is the best method in 

 most cases. 



REFERENCE 



VoELCKER and Hall. The Valuation of Unexhausted Manures. 



