SOILS AND THEIR PREPARATION 87 



First, then, let us think of what this soil is made, and 

 of how it came into being. Look at the surface of any old 

 stone-built church or house and you will see how every 

 stone is partly covered by moss or lichen or other lowly 

 plant. These plants are growing in soil — formed by the 

 slow action of rain and air on the surface of the walls. 

 Similarly, in the gradual pulverisation and decomposition 

 of rocks, has all soil taken its origin. Similarly also, as 

 a rule, have lowly plants been its first offspring, the 

 bodies of which have been afterwards incorporated with 

 their mother soil. By the further action of the weather, 

 coupled with the action of the accompaniments of the 

 decomposition of these early plants, the soil becomes 

 deeper, and becomes also furnished with dead vegetable 

 matter, or humus, without which none of the higher 

 and more developed plants are able to live. 



According to the nature of the original rock, and 

 according also to the sort of natural weathering " 

 or watering " to which it has been subjected, so will 

 the resultant soil be mainly sand or mainly clay, or an 

 equal mixture of the two. Mixed with these will 

 usually be found a certain amount of little stones or 

 gravel, and a certain amount of dark coloured humus. 

 In a soil which is nearly all sand, or in one which is 

 nearly all clay, few flowers will thrive, but in what is 

 called a loamy soil — that is, one in which clay and sand 

 are nearly equal — nearly all plants will grow and prosper 

 if other conditions be favourable. The presence of 

 humus in the soil is important in many ways, for not 

 only does it contain much that is essentia) food for plant 

 growth, but also it assists the earth in retaining that 

 moisture without which life is impossible. By its 

 chemical activity, also, it produces useful heat and 

 liberates stores of food from the mineral soil itself. 

 Therefore it is that we add dead leaves, farmyard 

 manure, sea-weed and the like to our garden soil. 



