Commercial Gardening 



rocks as silica or flint, sandstone, quartz, granite, &c., by the action of the 

 weather and water. The peculiarities of sand are: it is hard and gritty; 

 it will not float in water; its particles will not cohere readily even when 

 wet, nor can they be moulded into any shape for any length of time; it 

 will not hold water; it absorbs and radiates heat readily; and in a fine 

 condition its particles are blown about easily by the wind when dry. 



When mixed with clay, peat, loam, and other soils sand is useful because 

 it renders the soil more porous, warmer, easier to work, and better aerated 

 all valuable properties for plant growth. 



Clay. This is also composed of fine particles, but much finer than in 

 sand, and possessing different properties. The particles are soft and greasy 

 to the touch when wet, and can be moulded into any form; they also float 

 in water for a long time and make it " muddy "; they retain moisture for 

 a long time, and will not allow it to escape readily. When dry, clay cracks 

 and shrinks; when wet it expands, and becomes very slippery to the foot. 



Clayey soil by itself is fit only for making bricks, pottery, &c., the 

 finest chinaware being made of a whitish clay containing silica, alumina, 

 and water. When burned, clay undergoes marvellous changes. It is no 

 longer sticky, plastic, or impervious to water, and its particles are loose, 

 porous, and brittle. Even when wetted, burned clay can never revert 

 to its original plastic and slippery condition. In some places the clay soil 

 is often burned with the object of making it lighter, warmer, and more 

 porous. 



The advantage of clay in a garden soil is that it detains moisture and 

 manures, and prevents the temperature from rising too high in summer and 

 from sinking too low in winter, owing to its poor conductive powers. 



Loam. Sand and clay in about equal proportions, and with a quantity 

 of organic material, constitute a " loamy soil " the ideal soil for the hor- 

 ticulturist or agriculturist. When a loamy soil contains more sand than 

 clay it is called a " sandy loam "; when more clay than sand, a " clayey 

 loam". The various compositions may be expressed as follows: 



Chalk. A chalky soil is one derived from limestone rocks which, when 

 burned, yield the lime of commerce. Lime differs from chalk in not con- 

 taining carbonic acid gas; this was driven off in the burning. When lime 

 is burned it is known as quicklime; and when water is poured on this 

 it is readily absorbed, expansion takes place, and great heat is generated. 



