l^IPROVING POOR SOJLS. 375 



life of any future pl^nt of the same species, although, as Observations 

 we said before, not for any other kind, until, by a proper rrspectine"ihe 

 succession, this very matter be attracted and absorbed into improvement 

 the substance of other plants ; and thus Ave are enabled to °^ ^°°'^ ^"^^ ■ 

 point put the obvious principles that govern those rotations, 

 which the experience of all ages teaches. 



The great desideratum, or object of our enquiries, then 

 will be, what are the best means of bringing together a 

 fresh set of materials remaining in the soil ? And, what is 

 the succession best calculated to remove from the land, the 

 dregs of former crops ; or, what plants will best live and 

 thrive where others have previously been cultivated ? I 

 know it is the general opinion of men of experience, in 

 this part of the country, that fallowing can alone effect 

 the former, and it is the general practice to make the black 

 and white corn succeed each other, in order to effect the 

 latter. Let us, however, enquire a little further. I am 

 aware, that the fact (to account for which, I have ventured 

 to frame a theory) has been denied by authority*, long 

 celebrated in agriculture; I mean, "• that vhjcat cannot 

 be made to grow upon the same land, for two or three 

 years successively;" and we are referred to an experiment 

 made in a field belonging to Mr, Barlow, near York, fdr 

 the proof of the contrary; but what does the experiment 

 s^y? It says, that "plants of wheat were taken from a 

 situation, in which they had stood the winter, and trans- 

 planted into a field that had grown potatoes; had bedn 

 afterwards ploughed, harrowed, and rolled, and wele 

 pricked down an inch deep, and nine inches from each 

 otjier;" and, " that it is proposed to do the same f5r 

 several successive years, in order to determine the doubtful 

 poiijt, whether wheat can be raised for a number of suc- 

 cessive years, upon the same land;" and, " that, instead 

 of letting the land lie waste, under a summer fallow, it 

 may be made to produce a crop of cabbages, turnips, pease, 

 beans, potatoes, or summer vetches, as preparatory to its 

 being planted with "wheat.— Can this experiment militate ia 



frequently observed ; the fibrons roots of thorn, and many other 

 trees and plants, where they enter chalk ©r clay, kave b^hijad 

 them an ochre, or irony mark. < 



* Vide Dr. Hunl«r'i Circvlar X.««er. 



