32 A MANUAL OF FORESTRY. 



When the layer of peat is shallow, it can, after 

 draining, be mixed with the mineral soil below it, and 

 thus rendered fit for the growth of trees ; a good plan 

 is to take one or two field crops from the area, before 

 the trees are planted. 



If the layer of peat is deep, 3 feet and more, the 

 upper portion must be removed, and only the remainder 

 mixed with the mineral soil. The cut peat may be used 

 as fuel, but if not so required, it may be cheaper to burn 

 the upper layers in situ when sufficiently dried by 

 the draining, the ashes being mixed with the rest 

 of the soil. 



6. Accumulation of Raw Humus. 



This may consist of an accumulation of leaves, needles, 

 weeds, moss and twigs, which, from want of moisture in 

 the soil, or of heat or lime, has remained undecomposed. 

 The case only occurs in already existing woods. To 

 cure the evil, the wood must be thinned heavily, some 

 time before regeneration is contemplated, so as to 

 increase the admission of sunlight and air currents and 

 thereby the rate of decomposition. If this measure 

 proves insufficient, part of the humus must be removed, 

 and the rest mixed with the mineral soil. 



c. Dry Mould and Bituminous Humus. 



The first is formed by the decomposition of certain 

 lichens on over-dry soil ; the latter is the result of the 

 decomposition of heather and various species of Yacci- 

 nium. Both are unsuited for young plants, and they 

 should be removed. 



