278 ON THE SOILS AND SUBSOILS 



Heyer, director of the Forest Academy, Mliuden), is found in- 

 sufficient quantity in almost all varieties of soil. Tn addition, 

 rain, snow, dew, and hail are continually bringing fresh supplies. 



2. The Amount of Moisture contained in the Soil is of the utmost 

 importance for the supply of the rootlets of trees with the vast 

 quantity of water given forth through the leaves during the 

 annual period of vegetation. In order to satisfy this demand, 

 the soil must be capable of absorbing moisture, and of retaining 

 it. Loose sand, with a small percentage of clay, absorbs moisture 

 quickly, but has not the power of retaining it; on the other 

 hand, binding clay does not absorb moisture rapidly, or to a 

 great extent, but is exceedingly retentive. The admixture of 

 vegetable mould with the soil has the effect of modifying both 

 extremes. 



There are five degrees of moisture in soils : — 



(1.) Wet. — On lifting up a handful, water drops to the ground. 



(2.) Hoist. — On squeezing a handful, water drops to the 

 ground. 



(2.) Fresh. — On squeezing a handful, traces of moisture 

 remain on the hand. 



(4.) Dri/. — On squeezing a handful, no traces of moisture 

 remain on the hand. 



(5.) Arid. — On being merely rubbed, it flies off as dust. 



3. The Degrees of Looseness. — The more clay contained in a soil, 

 the more binding it is; and according as sand or lime is added 

 to, or occurs in its composition, the degree of looseness becomes 

 heightened. For the growth of timber binding clay is unfavour- 

 able, as it does not allow free entrance to moisture and air. On 

 the other hand, very loose soils, especially if wanting in depth, 

 are apt to become dry, and are exposed to the influence of frosts ; 

 while the trees, having no firm support in the shallow, unretentive 

 soils, often fall before the fury of wintry storms. Here, again, 

 both extremes are modified by the admixture of humus. 



4. Depth of the Soil favours the growth of all trees, since 



a. More moisture is absorbed, and is retained for a longer 



period of time, and 

 I. The roots have more extensively developed, the annual 



supply of sap is greater, and the cubic contents of the 



tree are greater than on shallow soil. 



The classification of soils according to depth may be, — 

 (1.) Very shalloiv — up to 6 inches in depth. 

 (2.) Shcdloiv — from 6 inches to 1 foot. 

 (3.) Middle Deep — from 1 foot to 2 feet. 

 (4.) Deep— horn 2 to 4 feet. 

 (5.) Very deep — over 4 feet. 



