72 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



An ordinary average sample of loam is seen to contain 3*84 

 per cent, of organic matter, 0'13 per cent, of nitrogen, 0*20 per 

 cent, of potash, 0*66 per cent, of lime, and 0*12 per cent, of 

 phosphoric acid. A garden bedding soil of fair texture will con- 

 tain a larger proportion of available nitrogen, as well as other 

 plant-food constituents, than the ordinary arable loam ; the 

 amount of nitrogen being nearly double, the potash considerably 

 larger, and the phosphoric acid four times as much. The rich 

 garden loam is about twice as valuable in the various chemical 

 ingredients as the garden bedding mould ; the exceedingly large 

 amount of lime — over 2 per cent. — would very materially assist 

 in the active nitrification of the larger percentage of organic 

 matter, which is shown to be nearly 8 J- per cent. In fact, Pro- 

 fessor Hilgard has pointed out that the presence of lime in a 

 soil, especially when associated with humus, much increases the 

 availability both of potash and of phosphoric acid, so that 

 smaller quantities of these constituents suffice when extra lime 

 is present. 



The rich pasture soil, in consequence of its extensive amount 

 of grass-root fibres, contains in the sample quoted 14^ per cent, 

 of organic matter, with 0'59 per cent, of nitrogen, about the same 

 amount of potash as the garden loam, but only one-half the 

 proportion of lime. The phosphoric acid, however, is exceedingly 

 high, amounting to 1 per cent., being the richest in the series. 



The leaf mould contains 17 per cent, of organic matter, with 

 nearly } 2 per cent, of nitrogen, a good quantity of potash, but 

 only small amounts of lime and phosphoric acid. 



The peat mould of France is high in most constituents, 

 especially in organic matter, and in nitrogen ; the potash and 

 phosphoric acid are, however, somewhat low in amount. 



The Ghent heath mould is remarkable for its enormous 

 quantity of organic matter. Much of this is stated to be in not 

 a very advanced stage of decomposition. Consequently the 

 quantity of fine mould passing through a \ in. mesh sieve is found 

 to be less than in the case of some other soils. These investiga- 

 tions show that the great value of the Ghent heath mould and 

 of the French peat mould for horticultural purposes rests 

 mainly in the excessive amount of fibrous-rooted material or of 

 leafy organic matter, with a correspondingly large amount of 

 nitrogen. It is these constituents which by their abundance 



