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PHYSICAL GEOGRAPHY. 



Dr. Jackson prepared an extensive sketch of the relations of geology 

 to agriculture, to which the attention of those interested in the subject 

 is invited, on account of the many valuable suggestions contained in it. 



USE OF FERTILIZERS. 



Formerly it was thought that the mineral constituents of plants were 

 of no great consequence in their growth. Experimental research indi- 

 cates that certain proportions of various mineral elements are essential 

 to the perfect growth of a plant, and* that if the proper ash-constituents 

 are not supplied, every part may be vigorously developed except the seed. 

 These researches have led to the extensive introduction of mineral fertil- 

 izers. 



In order to understand what kind of fertilizers should be applied 

 to the soil, the farmer should know, first, the exact composition of his 

 ground; second, of his crops; and third, of the proper fertilizers to be 

 applied. The statements already given will show in general the compo- 

 sition of the soils of the state. For more exact information, special 

 determinations should be made in each case. It will be possible to pre- 

 sent a few general statements in respect to the composition of the more 

 common farm products and commercial fertilizers. These analyses will 

 be a safe guide when one wishes to know what fertilizers must be applied 

 to the soil in order to restore what has been abstracted from it by the 

 removal of the several crops. The tables are derived from an essay on 



