CHAPTER X 



The Soil 



Four substances, combined in varying pro- 

 portions, form the soil or arable land : these 

 are sand or silex, clay, chalk and humus. 

 Each of these materials by itself would 

 produce a very poor soil quite unfit for 

 cultivation ; but in combination with each 

 other they fulfil the conditions that are re- 

 quired for fertility. Generally, arable land 

 contains all four, with one or the other pre- 

 dominating. The soil takes its name from 

 its chief component. The terms siliceous 

 soil, clay, calcareous and humiferous soils, 

 are used to designate arable ground in which 

 silex, clay, chalk or humus respectively 

 predominate. 



Sand consists of very small fragments of 

 a very hard rock, which is sometimes opaque 

 and sometimes as transparent as glass, and 

 always easily recognised by its property of 

 emitting a spark when struck with steel. 



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