ARTIFICIAL MANURES AND HORTICULTURAL PRACTICE. 



39 



as in lettuce, spinach, or asparagus, &c. ; all this means in the 

 end nothing less than that the chance of the horticulturist for 

 controlling the quality as well as the quantity of his crops is 

 daily improving. 



We are told by Dr. C. A. Goessmann, " That to feed plants 

 intelligently implies possession in a fair degree of two kinds of 

 information, namely a knowledge of the special wants of the 

 plant under cultivation as regards the absolute amount and rela- 

 tive proportions of the various essential elements of plant-food ; 

 and also a familiarity with the composition and the general 

 physical properties of the different kinds of manurial matter at 

 our disposal." 



All our cultivated plants, whether in the garden, the orchard, 

 or in the conservatory, contain the same elementary constituents, 

 yet no two of them are in the same absolute amount and rela- 

 tive proportions. Each plant has its especial wants at different 

 stages of its development. Succulent and rapidly-growing 

 vegetables require an abundant supply of nitrogen in an avail- 

 able form during their early periods of growth ; flowers and 

 fruit-trees require phosphatic food when blooming and develop- 

 ing seeds or fruit ; grape-vines need a large amount of available 

 potash during the formation and maturing of the grapes for the 

 production of a rich and sugary juice ; while potatoes require 

 nitrogen and potash for the production of starch in the tubers. 



The subject of my lecture being more directly in connection 

 with the feeding of plants than with their chemical composition, 

 I shall not trouble you with many analytical results. Neverthe- 

 less, in order to illustrate how plants of the garden may, and do, 

 vary in their chemical constitution, I will direct your attention 

 to a few statistics bearing upon the question. 



Table I. gives the amount of selected constituents taken from 

 the soil by the growth of one ton of various descriptions of vege- 

 tables. Column 1 shows the number of pounds of dry substance 

 yielded ; the second and third columns give the quantity of 

 nitrogen and of ash in the fresh vegetables ; while the fourth and 

 fifth columns give the number of pounds of potash and phos- 

 phoric acid yielded by the ash of the plants analysed. 



