50 A MANUAL OF FORESTRY. 



As a set-off against these advantages the following 

 drawbacks must be mentioned : 



(1.) On steep slopes loosening the soil maybe followed 

 by denudation, as rain-water can more easily carry it away. 



(2.) Frost-lifting may occur more frequently. 



(3.) It may attract injurious insects, such as the 

 cockchafer, the larvae of which are very destructive to 

 roots. 



The degree of loosening, and the depth to which it 

 may reach, depend on the original condition of the soil. 

 Hard or wet soil requires more ; naturally loose soil 

 less or no working. 



In some cases the actual process of loosening the soil 

 must be preceded by the removal of an obstructive 

 surface covering, such as woody shrubs, weeds, grass, 

 moss, ferns, heather, raw-humus, etc. ; in other cases 

 this is not necessary. The loosening itself can be done 

 in a variety of ways; by means of tools, such as the 

 plough, harrow, rake, hoe, or spade ; by allowing it to 

 be broken up by swine ; or by a temporary cultivation 

 of field crops. Whether the one or other is preferable 

 depends on the method of sowing and the cost of the 

 operation. 



Too much moisture may prevent or retard germina- 

 tion, may obstruct aeration of the soil, or render 

 it cold and cause the seed to rot. These incon- 

 veniences can be prevented either by a better distribu- 

 tion of the water, or by draining. The latter plan 

 should be restricted to cases where the moisture is 

 really excessive, and where no injurious effect upon 

 adjoining areas is likely to be produced. In forestry it 



