ROTATION OF CROPS. 223 



without the occasional addition of manures, they will be found 

 gradually to diminish in quantity, till they reach a point when 

 they will scarcely pay the expenses of cultivation. We mean 

 to be understood as affirming this of all crops and all soils 

 however naturally fertile the latter may be, unless they are 

 such as reeeive an annual or occasional dressing from the over- 

 flow of enriching floods, or are artificially irrigated with water, 

 which holds the necessary fertilizing matters in solution ; and 

 ti'-h art' nut exceptions, but receive their manure in another 

 form, unaided by the hand of the husbandman. Neither an*. 

 <>/'/ innuhwft (mowing lands filled with the natural or unculti- 

 vated grasses or whatever of useful forage they choose to bear) 

 j.timss to this rule, for though they may part with a portion 

 of their annual crop in the hay, which is removed, and which 

 is not returned as manure, and by a partial rest or pasturage 

 appear to sustain their original fertility, yet if the true cha- 

 racter of the various plants which they produce were accu- 

 rately observed, (all of which are indiscriminately embraced 

 under the general head of grass or hay,) it would be found 

 that the plants gradually change from year to year ; and while 

 some predominate in one season, others take their place the 

 year succeeding, and these again are supplanted by others in 

 an unceasing round of natural rotation. Another illustration 

 of rotation may be observed in the succession of forest trees 

 that shoot up on the same soil, to supply the places of such of 

 their predecessors as have decayed or been cut down. Thus 

 the pine and other of the coniferae, are frequently found to 

 usurp the place of the oak, chesnut, and other deciduous trees. 

 This occurs sometimes partially, but in repeated instances 

 which have come within our notice, forests have been observed 

 to pass entirely from one order of the vegetable creation to its 

 remote opposite, the seeds or germs of which, (the product of 

 an ancient rotation,) had been lying dormant for centuries 

 perhaps, waiting a favorable condition of circumstances and 

 soil to spring into life. 



Many choice secondary bottom lands, and others munifi- 

 cently supplied by nature with all the materials of fertility, 

 have by a long succession of crops been reduced to a condi- 

 tion of comparative sterility. Yet it will have been found in 

 the progress of this exhaustion, that after the soil ceased to 

 give an adequate return of one crop, as of wheat, corn or to- 

 bacco, it would still yield largely of some other genus which 

 was adapted to it. These lands when thus reduced and turned 

 out to commons for a few years, will again give crops much 



