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on which soils shovild be improved, and rendered proper for 

 the food of plants. It has been said above, and it cannot be 

 too often repeated, or too earnestly enforced, that it is by 

 principles drawn from nature, and elucidated by science, that 

 any real progress can be made in an art hke the one under 

 discussion, where nature and science must unite in regulating 

 the process, and art must follow in the track which they 

 prescribe. 



