4 



sub-soil, the latter being the intermediate stage between the rocks and the soil, 

 and as yet not sufficiently decomposed to form soil capable of supporting plants. 

 Shallowness of soil or a deficiency of water or food-supplies in the soil are at once 

 evident from the stunted appearance of trees, generally accompanied by an 

 abnormal development of the root system. A very remarkable instance of this 

 is seen in the Cashaw,* the u Mesquite" of Texas and Xew Mexico, the condition of 

 which affords almost certain indications in those regions of the depth of the water- 

 level ; when it attains the demensions of a tree, the water-level will be found with- 

 in 40 or 50 feet of the surface ; when it has the appearance ot a good bush, within 

 50 or 60 feet ; when the stems are only 2 or 3 feet high, the roots have had to de- 

 scend more than 60 feet. So that a fairly correct estimate of the depth and 

 quality of soil may be formed from considering the height of the trees, the de- 

 velopment of their crown of foliage, and the condition of the underwood and bush 

 which cover the soil. 



The chemical composition of the soil is not of such importance in woods as in 

 Agricultuie, f >r trees take up only about half the mineral food demanded by agri- 

 cultural crops, as is shown in the following table : — 













6 



bo 





Sulphuric Acid SO:*. 



93 



Average of 



lantity c 



O 



d 

 M 



d " 



>ric Acic 



-+=> 

 aa 



a 





H 



11 



Eh 



Silica Si 



Potash 



| Limo Cs 



Magnesi 





o 



u 

 o 



— 



o 



iMixed agricultural crops 



235 



37 



78 



43 



17 



28 



11 



21 



"Woodland growth — timber 

 and leaves 



126 



29 



11 



62 



10 



8 



3 



3 



"Woodland growth — timber 

 only 



19 



1.6 



4 



9 



2 



1.4 



0.4 



0.6 



It will also be seen from the table that m woods where the leaves drop and de- 

 compose, returning their constituents again to the soil, the demands upon the 

 soil are very small indeed as compared with crops. 



But of the sum-total of the factors which go to make up a fertile soil, its phy- 

 sical condition, — depth, porosity, consistency, etc., is of far greater importance 

 generally than the chemical composition. 



SEED. 



QUALITY. 



In using seed for the propagation of trees, it is important to use only seed of 

 the best quality. The chief point in estimating the qunlity is its perfect ripeness, 

 but its goodness also depends on its weight and size, its age and origin. 



Ripeness. If the seeds are not quite ripe, the greater number do not germinate ; 

 the seedlings are weak ; the plants are never as strong as those from ripe seeds, 

 being more liable to attacks from insect pests and fungoid diseases all through 

 their life, and many die before reaching maturity. 



Size and weight. In selecting seeds of any particular species, the largest and 

 heaviest seeds only should be sown ; as a larger percentage germinate, and the 

 seedlings are stronger, getting a better start in life, which generally gives the plant 

 throughout its life a great advantage over plants from small light seeds. 



Age. Seeds germinate most readily the sooner they are sown after becomiag 

 quite ripe. It is an advantage that they should germinate quickly after sowing, 

 for they more quickly escape attacks of ants, birds, and other dangers, and have a 

 start over weeds. Besides, seeds lose their power of germinating, more or less 



* Prosopia j uii flora. DC. 



