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reach of the farmer, the former is to some extent within his 

 control ; and when deficient may be supplied in 'the quantity 

 required. 



The fertility of a soil depends upon its containing among its var- 

 ious constituents, all those that are suited to the nourishment, and 

 necessary to the growth of plants. When such exist in adequate 

 supply, no foreign additions to the soil are required ; and in 

 some instances this is found to be the case to such an extent as 

 to permit the cultivation of tlie same crop upon the same land for 

 a long series of years, without any perceptible diminution of the 

 quantity of the product. Such is the case to a certain extent in 

 our western country, where it has been said that in the neighbor- 

 hood of Yincennes, a settlement on the Wabash, of the same date 

 as Philadelphia, the same land has been under corn for more than 

 sixty years in succession. Such a state of things too may occur, 

 where the natural fertility of the soil, is maintained by the opera- 

 tion of some extraneous cause, such as the periodical overflow of 

 rivers, of which that of the Nile is a famihar example. Expe- 

 rience, however, teaches us that, in time, the most fertile soil, 

 unless the elements of its fertility are constantly renewed by the 

 operation of natural or artificial causes, must grow gradually less 

 and less productive, and in the end become wholly exhausted. 

 The diminished crops on the originally fertile and productive lands 

 of Western New York, are an evidence of this deterioration, and 

 the abandoned old fields of Virginia of this entire exhaustion. 



As the great object of agriculture is . to increase the quantity 

 and improve the quality of the vegetable food of men and ani- 

 mals, the great object of the farmer is to maintain and increase 

 the fertility of his fields, by restoring or enlarging the supply of 

 nourishment for plants, because in no other way can the object 

 of his art be attained. 



This restoration of fertility, this adequate supply of nourish- 

 ment, is sought for and procured in various ways, by the operation 

 of some mechanical process, as ditching, draining, deeper 

 ploughing, by a cultivation conducted on scientific principles, ia 

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