2 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



composition between the finest and the coarsest material : in the south 

 and south-east of England the coarsest particles are mainly silica, 

 which is very insoluble in water and therefore not easily reducible 

 in size by the washing of rain, while the finest contains much more 

 iron, alumina, &c. In the north, however, the coarse particles contain 

 other constituents also, and are indeed more like the original rock; 

 this is shown in the following table : 



Composition of Soil Particles. 





Silica (SiO f ). 



Aluminc 



1 (A1.0,). 



Iron Oxide (Fe,0 8 ). 





S.E. of 

 England. 



Aberdeen. 



S.E. of 

 England. 



Aberdeen. 



S.E. of 

 England. 



Aberdeen. 



Fine gravel 

 Coarse sand . 

 Fine sand 

 Silt 



Fine silt 

 Clay . 



94'4 



939 

 94- O 



8 9 '4 

 f 84- 1 

 t 64-3 

 f 53'2 

 I 49- 0 



850 

 839 

 739 

 70-1 



67-2 

 44- 1 



30 

 1-6 

 20 

 5*1 

 / 7-2 

 \ 193 



f 212 



t 29-8 



86 

 93 

 135 

 14-0 



189 



276 



21 

 12 

 12 



i*5 



( 26 



t 76 

 r 132 

 \ 131 



II 

 II 



4- 2 



5- 8 



7-8 

 21-8 



Presumably the difference arises from the circumstance that the 

 soils in the north are mainly formed direct from the rock, e.g. from 

 granite in Aberdeen ; while in the south they have undergone two or 

 three long immersions in sea water — in the Jurassic sea and in the 

 sea of Cretaceous times — besides other wanderings calculated to allow 

 of the removal of everything that could be dissolved out. This 

 difference in composition may be expected to affect the properties of 

 the soil, and so we should expect to find the northern soils differing 

 from the southern. Agricultural observations are accumulating : 

 it would be interesting if horticulturists could accumulate observations 

 also. 



Perhaps the most striking property of these mineral particles is 

 their astonishing permanence. It used to be thought that weathering 

 went on sufficiently quickly to produce appreciable quantities of food 

 for plants. Eighty years ago soil chemists looked upon the subsoil 

 as a storehouse of plant food ; they advised bringing up some of the 

 subsoil to the surface in autumn, so that weathering could go on 

 during winter and provide a stock of plant food for the spring. 

 Practical agriculturists devised appropriate methods. In the fifties 

 and sixties of the last century a great discussion was started by 

 the Rev. S. Smith of Lois Weedon * as to the feasibility of growing 

 wheat in this manner ; manual labour was cheaper than manure, 

 and therefore trenching— real trenching, not bastard trenching— was 

 recommended as a suitable substitute. But many years of experi- 

 ments have shown that cultural processes based on weathering are of 



• A Word in Season. Rev. S. Smith, 1849 : amplified in 1886 to Lois Weedon 

 Husbandry. 



