CROPPING AND MANURING. 



191 



TRIENNIAL SYSTEM. 



Fecundity. 



115 deg. 109 deg. 



By which course, land would gain six degrees of fer- 

 tility in nine years, provided the manure was that of well- 

 fed cattle ; but if principally straw, it probably would oc- 

 casion no amendment. 



1691 deg. 139 deg. 



♦The augmentation of fertility is here added, because of the culture 

 bestowed upo^the potatoes as a fallow crop, the value of which is 

 considered equal to 10 degrees. 



