ARTIFICIAL MANURES AND HORTICULTURAL PRACTICE. 



Jl 



do the marketable portions ; teaching us the advisability of 

 returning to the soil all the unsaleable products. 



There are quite a number of ingredients that enter into 

 the composition of plant-ash — namely, potash, soda, magnesia, 

 lime, phosphoric acid, sulphuric acid, oxide of iron, chlorine, &c. 

 All, or nearly all, of these are proved to be necessary to the full 

 development of horticultural plants ; but I have selected those 

 which we find in actual practice necessary to return to the soil, 

 and are willing to pay for in artificial manures. The other 

 elements take care of themselves in nearly all fertile soils. 

 Potash, phosphoric acid, and nitrogen are the three constituents 

 generally taken into consideration, and the poorer the soil in 

 what may be called its natural fertility, the more complete must 

 be the restoration of these important ingredients that are carried 

 away in the crops, if productiveness is to be maintained or 

 increased. 



In order that plants may obtain all the fertilising substances 

 they require, it is necessary that there be a large excess of them 

 in the soil, probably double the amount shown by an analysis of 

 the crops grown. If a gardener proportions his supply of 

 manure to the waste caused by the growth and removal of his 

 crops, he will keep up the fertility of his soil to the degree in 

 which he found it ; and if he gives more judiciously he will 

 gradually increase its fertility, and enable it to withstand 

 drought and other adverse influences more effectually. 



The small amount of dry substance in the various vegetables 

 enumerated in Table I. shows how largely these products are 

 composed of water, and points to the fact that if the gardener is 

 to ensure vigorous and uninterrupted growth in his vegetables 

 he must have a sufficiency of moisture in the soil in immediate 

 proximity to the mass of root-fibrils which branch out from the 

 root-stock. In ordinary garden practice, farmyard or stable 

 manure is not only largely relied upon, but it is often applied in 

 exceedingly large quantities. It is probable that independently 

 of the liberal supply of all necessary plant-food constituents in 

 farmyard manure, its beneficial effects are in a considerable 

 degree due to its influence on the mechanical condition of the 

 soil, rendering it more porous, hence more moisture-sustaining, 

 and, therefore, more easily permeable to the surface roots, upon 

 the development of which the success of garden vegetables so 



