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fcvcral years in fucccflion, 'till its ftrcrigtH 

 exhaufted, it would be equally incapable of I 



ing any other fort of grain, roots, or gr.dfes, as 

 if it bad borne each in fua rding to the 



llfual courfc of cropping; which thews that 

 fertility of land may be as COtnpl \haufted 



by any one plant as by them all, which could not 

 poflibly happen, if the particles of nouriihment 

 each drew were only proper to each, and could 

 not be abforbed by any other. 



It is true, fottie kinds of plants exhauft and 

 impoverifh the foil much fader than others; as 

 perhaps three crops of wheat would impoveriih 

 the land it grew on, as much or more than four 

 of barley; but yet, if planted with cither 'till it 

 would bear no longer, it would be found equally 

 incompetent to the growth of every other kind of 

 plant, excepting fuch unprofitable ones as are the 

 natural produce of ftcrile foils. 



The true conclufion therefore is, if land be ex* 

 haufted, whether by the growth of one particular 

 kind of plant, or of many kinds in fucceflion, 

 its fertility mutt be reftorcd before it can bear 

 a profitable crop of any other kind of vegetable, 

 though it had not been planted with it for an age 

 before. 



D 3 The 



