68 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



TABLE II. --Mechanical Analysis of Different Descriptions of Soil, 

 cut to 9 inches deep. 





Arable 

 loamy 

 soil 



Rich 

 pasture 

 soil 



Alluvial 

 pasture 

 soil 



Rich 

 water 

 meadow 

 soil 



Heath 

 mould 

 (Ghent) 







% 



a/ 

 /o 



9-2 

 28-1 

 52-7 

 10-0 



o/ 

 fo 



% 



% 



Gravel . 

 Sand 



Clay and chalk 

 Organic matter 





8-7 

 62-9 

 19-9 



8-5 



0-3 

 72-2 

 20-1 



7-4 



1-6 

 51-4 

 111 



35-9 



o-o 



34-0 

 2-0 

 64-0 



Total . 





100-0 



100-0 



100-0 



100-0 



100-0 



The quantity of gravel is seen to range from less than 

 \ per cent, to over 9 per cent. The sand ranges from 28 to 

 72 per cent. The clay, including lime and soluble silica, ranges 

 from 2 per cent, in the Ghent heath mould to about 52| per 

 cent, in the rich pasture soil. The organic matter ranges from 

 about 1\ per cent, to 64 per cent. The Ghent heath mould is 

 composed of more than five-eighths of its total weight of 

 organic matter. It may, therefore, be easily understood that 

 the ready-formed plant-food in soils, whether of mineral con- 

 stituents or of nitrogen, is a very fluctuating quantity, often 

 falling below the needs of a particular crop, as regards one or 

 other ingredient. It is only the very rich virgin soils, formed 

 by breaking up of natural pastures of newly settled countries, or 

 such soils as the Ghent heath mould, as quoted in Tables II. 

 and III., that are practically inexhaustible. 



The Soil as a Souece of Plaxt Food. 



In order to start with definite notions about the inherent 

 fertility of soils, I may state that where any plant, however lowly, 

 has once grown and died away, its remains gradually decay and 

 add a little vegetable or organic matter to the soil, rendering it 

 thereby capable of growing a better plant the next season. 

 As the soil becomes richer in carbonaceous and vegetable 

 matters, higher organised plants will occupy it ; these pass 

 through the same phases of life as the plants of simpler 

 structure, and enrich the soil at an increasing rate by the 

 expanded flora, as well as by the greater bulk of their products 



