$r\ , VEGETABLE GAKDENING. 



, Composition of Soils. With the exception of 

 l>ld,ck peaty eoils, which are mainly of vegetable 

 origin, all soils have been formed primarily by the 

 accumulation of particles of mineral materials, con- 

 sisting chiefly of sand and clay, along with other 

 inorganic substances. And although these materials 

 form the basis of all fertile soils, they are, by them- 

 selves, incapable of supporting plant life. It is 

 only when they become mixed or enriched with 

 organic or vegetable material in sufficient propor- 

 tions, along with an adequate supply of lime, that 

 the soil becomes really fertile and capable of pro- 

 ducing heavy crops of the best quality. 



It follows that the main ingredients in the com- 

 position of a good fertile soil are sand, clay, humus 

 or organic matter, and lime. Further, these in- 

 gredients contain and are capable of providing in 

 suitable form quite a number of substances required 

 for the growth of crops. 



Sand. This consists principally of grains of quartz 

 or silica, frequently coloured by the presence of oxide 

 of iron. Sand does not cohere readily, and has the 

 mechanical effect of keeping a soil free, porous, and 

 well ventilated. It also absorbs and radiates heat 

 quickly ; consequently, soils containing a fairly large 

 amount of sand are looked upon as warm soils, pro- 

 ducing early and rapid growth and hastening the 

 maturity of the crops. 



Clay. This consists of minute particles of alumina, 

 quartz, and other minerals. Clay is very cohesive, 

 wet, and cold, but when present in the right propor- 

 tion it enables a soil to hold moisture and soluble 

 plant foods; and although slow to warm up, once 



