SOIL. 31 



chiefly clay and less than 5 per cent of lime, with about 5 per cent of 

 ferric oxide as colouring matter. This includes loam and sandy loam. 



Clayey Soil, containing 50 per cent or more of clay. This includes clay 

 and loamy clay. 



Limy Soil, with 10 per cent or more of carbonate of lime. This in- 

 cludes lime, clayey lime, loamy lime, and marl. 



Sandy soil feels gritty when slightly moistened, is easily heated or 

 cooled, does not well retain moisture and soluble plant - food, and is 

 therefore an inferior soil, on which trees need a large growing-space, do 

 not maintain close canopy, soon fall off in rate of growth, and produce 

 little seed. Easily warmed by day, it encourages early germination of 

 seed, early movement of sap, and early flushing of foliage in spring ; but 

 as it cools rapidly at night, the young tissues are exposed to damage by 

 late frost. 



Clayey soil sticks to the tongue, smells of ammonia if breathed upon, 

 feels fatty if rubbed between thumb and forefinger, and takes a polish 

 if rubbed with the thumb-nail. It is usually, tinged with iron, and of 

 a grey, yellow, or brownish-red colour. It is cold, stiff, impermeable to 

 moisture, and apt to get water-logged and marshy. Admixture of sand 

 tends to modify these characteristics. As soluble salts are not easily 

 washed out, clay soil contains large food-supplies, and tree-crops have a 

 better leaf-canopy than on sandy soil. Owing to low conductivity of heat 

 the active vegetation is late of beginning in spring. 



Limy soil effervesces if nitric acid be dropped on it, and is apt to be 

 shallow ; but woods in close canopy often show fine growth. When limy 

 soil has deteriorated through insufficient leaf -canopy or clear-felling, the 

 soil-moisture soon evaporates, the finer earthy particles are washed away, 

 and the soil becomes shallow, dry, hot, and unproductive. 



Loamy soil resembles clay more than sand, but neither feels fatty 

 when rubbed between finger and thumb, nor takes any definite polish 

 when burnished with the finger-nail. It is a mild soil, in which the 

 absorption and retention of soil-moisture depend greatly on the nature of 

 the subsoil ; and it is suited for growing almost every kind of tree. 



Any of the above soils may also be gravelly or stony. 



The Physical Properties of Soil, which are far more im- 

 portant than its chemical or mineral composition, and all of 

 which, with their innumerable variations, act and react on 

 each other in determining the quality of any given land, 

 include (1) Depth, (2) Stiffness, (3) Soil-moisture, and (4) Soil- 

 temperature. 



