1894.] PUBLIC DOCUMENT — No. 33. 243 



We prefer to-day to speak of feeding plants. To secure 

 the best possible results in feeding plants requires informa- 

 tion with regard to the three following points : namely, with 

 relation to the physical and chemical character of the soil in 

 question ; a knowledge of the special wants of the plant 

 under cultivation, as regards the absolute and relative pro- 

 portions of the various essential articles of plant food re- 

 quired ; and a familiarity with the composition and the gen- 

 eral physical properties of the different kinds of manurial 

 matter at our disposal. 



A brief statement of the principal results of a systematic, 

 scientific examination into the circumstances which control a 

 healthy and vigorous growth of plants may not be out of 

 place here. 



First, All our cultivated plants on the farm, in the garden 

 and in the orchard contain the same elementary constituents, 

 yet no two of them in the same absolute amounts and relative 

 proportions. The list comprises carbon, hydrogen, oxygen, 

 nitrogen, sulphur, phosphorus, potassium, sodium, calcium, 

 magnesium, silicon, chlorine (manganese?). 



Second. These plant constituents are furnished in part by 

 the surrounding atmosphere, in part by the soil, and some in 

 varying proportions by both. 



Third. The essential plant constituents are not needed 

 in different plants in the same invariable proportions at the 

 various successive stages of growth, but are wanted at differ- 

 ent stages of growth in different absolute amounts and rela- 

 tive proportions. Each kind of plant has its especial wants 

 at different stages of its development. (Grains require much 

 nitrogen in an available form during their later period of 

 growth, when blooming and forming seed, while grape vines 

 need a large amount of potash during the growing and matur- 

 ing of the fruit, etc ) 



Fourtli. The absolute amount of the essential mineral 

 constituents may vary in the same kind of plant when raised 

 on different soils and in different climates without, as a rule, 

 affecting the general character of the plant ; yet it appears, 

 however, that not one of the essential elements can to any 

 extent replace another one without affecting more or less 

 seriously the amount and relative proportion of the organic 



