1853. THE PHILADELPHIA FLORIST. 361 



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{*} The above theory although supported by very high authority, fa m) 

 cP gradually giving way to the following, viz : That although the bulk *V) 

 I of plants is made up of the same primary elements, yet, different i 

 species require very unlike proportions of these elements, so that 

 each kind of plant has a characteristic formation peculiar to itself. 

 There is considerable variety in this respect among the different 

 tribes of plants, each seeming to grow most advantageously when 

 supplied with ingredients abounding in their distinguishing elements. 

 It follows, then, that if the various substances required by a plant for 

 its healthy growth, are deficient in the soil, that plant will not thrive, 

 although a plant of different formation may grow luxuriantly upon it. 

 From this it appears that the reason why a crop if constantly grown 

 upon one spot, will yearly diminish in productiveness, does not arise 

 from a repletion of any substance, but rather from exhaustion; and 

 that the same crop may be successfully grown upon the same soil for 

 an indefinite number of years, by annually supplying those elements 

 extracted by the crop. This might be practicable if the exact amount 

 of these substances Were known, but so far as present knowledge ex- 

 tends there is no accurate, practically useful information on the sub- 

 ject, sufficient to warrant its adoption. In a practical view it is evi- 

 dent from either of the above theories, that a change of crop is an 

 essential requisite to successful cultivation. 



In cultivating garden vegetables, there is ample room and facilities 

 for a frequent change of crop, and it may also be remarked that there 

 is a wide field for experiment in ascertaining the kinds best suited to 

 succeed one another in a regular system. In general, long-rooted 

 plants as beets, carrots, parsnips, &,c, should be followed by those 

 that root near the surface, and if the manure applied to the former 

 crops has been put well down, it will, on the soil being again turned 

 over, bring its remains in a position for immediate benefit to the 

 latter. 



Plants that are grown for their seeds, should be followed by those 

 grown for their leaves. The seeds of all plants contain a larger 

 amount of mineral ingredients than their leaves, and will in conse- 

 quence exhaust the soil to a greater extent than crops used before the 

 seed ripens. Early summer crops should be followed by those to be 

 used in the fall and winter. In reducing these into practice, two 

 methods may be adopted ; either by having only one crop at a time, 

 and when that is removed, immediately succeeded by another ; or, 

 have two or more crops on the same patch, so arranged, that the one 

 will be removed before it interferes with the growth of the other. In 

 i illustration of the first mode, a piece of ground may be sown with ) 

 - early peas, which will be cleared off in time for a crop of turnips, A 

 \^ beets, or spinach, or, a crop of early potatoes succeeded by a plant- (S 



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