PERCENTAGE OF ASH 



83 



is liable to be rather misleading if it be taken as a guide to 

 the food requirements of any particular crop, or the amount 

 of plant food returned per acre per annum by the fall of the 

 leaves. For, before any correct conclusions can be arrived at, 

 the total weight of leaves produced per acre per annum must 

 be^ascertained. Analyses show that the percentage of Ash 

 per unit of -weight is far greater in deciduous broad-leaved 

 trees than in conifers. This is shown by the following 

 table : 



As far as the chemical constituents are concerned, the 

 best trees to plant on really poor soils are : 



Birch, Scots, Corsican, and Austrian Pines, Aspen 

 Poplar, Acacia, Mountain Ash, and White Alder. 



The trees requiring most plant food are : 



Beech, Hornbeam, Spanish Chestnut, Silver Fir, Ash, 

 Elm, Oak, Sycamore, and Black Poplars. 



Some trees show a preference or a dislike to certain 

 minerals in the soil. 



Thus, any excess of lime is usually detrimental to 

 Douglas Fir, Weymouth Pine, Spanish Chestnut, Pinus 



