38 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



will contain more than 200 lb. of nitrogen, while the 150 lb. of 

 nitrate of soda will contain only about 28J lb. of nitrogen. And 

 yet, that the great effect produced by the nitrate of soda is due 

 to its nitrogen content there is abundant evidence. 



Why, then, does not the 200 lb. of nitrogen in the farmyard 

 manure do as much service as the 23J lb. of nitrogen in the 

 nitrate of soda ? Simply because the nitrogen in the dung is in 

 the form of an organic compound, and has to be converted into 

 nitrate of lime before the cucumbers or other plants to which it 

 may be applied, can use it ; while the nitrogen in the nitrate of 

 soda is exceedingly soluble, and is available as plant-food at 

 once. 



Plants are set in pots of soil, yet few persons realise how 

 they starve in such a small quantity of material, how they sicken 

 and fall victims to fungi ; how they suffer from decaying roots, 

 simply because they lack nourishment of a suitable kind. Dr. 

 Wagner, who may be quoted as an authority on this matter, 

 says, " It is impossible to state how much more easily and con- 

 veniently, and how much more successfully, and with what 

 greater financial advantage vegetable gardening, fruit culture, 

 flower raising and growing, could be conducted if a rational 

 system of plant-manuring were introduced." I myself am per- 

 suaded that a great future is in store for the horticulturist if he 

 will but study the composition of artificial manures, and their 

 adaptation to the needs of plants, so as to raise crops and place 

 them on the market out of season. 



A system of manuring may be called well devised or rational 

 when it is based upon the results of a careful examination into 

 the chemical composition of the plants under cultivation, and on 

 a due consideration as to their natural capabilities for availing 

 themselves of the needed food, both from the atmosphere and 

 from the supplies within the soil. 



The object sought in cultivating plants is usually to produce 

 a growth in some of their parts that is unnatural to the species 

 in its native habitat. This part may be the flower, the seed, 

 the fruit, the stem, or the leaves. Or, again, the object may be 

 to obtain an extra large amount of sugar as in grape production, 

 or of starch as in the growth of potatoes, or it may be to pro- 

 duce leaves with more cellular substance and less fibrous matter 



