266 



GUANO. 



Manuring ivitli guano. 



In Cunnersdorf, the increase of produce obtained in 

 1851, over the unmaniired field, amounted to — 



By farm-j^ard manure (180 cwt.) . 337 

 By guano (379 lbs ) . . .765 



straw Ratio 

 lbs. lbs. 



1745 = 1 : 5 



3028 = 1 : 3- 



The field at Cunnersdorf was naturally rich in those 

 ingredients which we have designated as S^ (straw) con- 

 stituents (silicic acid, potash, lime, magnesia, iron), and 



