82 



PLANTING 



acid lost by the removal of mature timber has already been 

 noticed. But it is necessary to note that under coppice 

 systems, the loss to the soil of mineral plant food and of 

 nitrogen is more than double the loss sustained by removing 

 mature timber. This is evident from analyses, which show 

 that the percentage of Ash constituents in various parts of 

 trees varies considerably, as is shown by the following 

 table : 



* The heartwood of a tree contains less ash than the sapwood ; also, most of the 

 nitrogen in timber is found in the sapwood, there being hardly any in heartwood. 



In a general way, it may be said that broad-leaved trees 

 remove more valuable mineral food from the soil than 

 conifers, that Beech removes more than other deciduous 

 trees, and that Silver Fir removes more than the Pines or 

 Spruces. But the amount is so small that the artificial 

 manuring with " cinereals " is not necessary. 



Though, were leaves habitually removed for litter, etc., 

 the loss of plant food would soon be evident. 



It will be noticed that the annual requirements of trees 

 for timber and leaves, amount, in the case of potash and 

 phosphoric acid, to less than half of that removed per acre 

 per annum by cereal crops, and that the amount of lime 

 required for trees is nearly 5 times that removed by cereal 

 crops, but that, as the leaves contain most of the lime, 

 potash, and phosphoric acid, these minerals are annually 

 returned to the soil in an available form. 



It should be remembered that any analysis of tree leaves 



