CHAPTER XII 



PLASTER OF PARIS IN AGRICULTURE 



IN agriculture plaster of Paris has by no means 

 the importance of lime ; nevertheless it produces 

 excellent results on clover, sainfoin, and lucerne. It 

 is used in the spring for sprinkling the young leaves 

 when they are still damp with the morning dew. 

 Still, foggy weather is the most favorable for this 

 work. Plaster also acts well on rape, flax, buck- 

 wheat, and tobacco, but has no effect on cereals. 



"The intelligent farmer puts plaster of Paris to 

 still another use. In every dunghill there is always 

 going on a slow combustion, or fermentation, giving 

 forth ammonia in vaporous form ; and this ammonia 

 escapes into the air as a total loss, whereas it ought 

 to be retained as far as possible in the manure, since 

 the compounds of ammonia constitute the source 

 whence plants obtain nitrogen. Therefore to pre- 

 vent this waste, plaster is sprinkled over the dung- 

 hill. Sometimes, too, it is sprinkled over each layer 

 of manure as the pile rises. The plaster absorbs 

 the ammoniac vapors, gives them a little of its sul- 

 phuric acid, and converts them into a compound, 

 sulphate of ammonia, which is proof against vapor- 

 ization. Hence we say that plaster of Paris fixes 



