138 FOREST LAND. 



I 



be supposed that, under a system of over-crop 

 ping, or as in Scotland it is emphatically 

 termed a scourging system, it will not at 

 length give way, and when its impoverishment 

 once takes place, they may be assured it will 

 be a matter very difficult, or it may be im 

 practicable, to restore it to anything like ori 

 ginal fertility. 



This observation more particularly applies 

 to land which has been reclaimed from forest. 

 Alluvial soil by deeper and deeper ploughing 

 may be kept in a productive state for a longer 

 time, and when it sickens, as sicken it must, 

 from constant working without feeding, it may 

 perhaps be revived by stimulating manures, or 

 by being laid to rest for a sufficient time un 

 der grass. Even in this case, prevention be 

 ing better than cure, it were unwise to dete 

 riorate the soil by overcropping when the 

 means of preserving its fertility are at hand. 



But as to land cleared from forest, the pro 

 ductiveness of it seems to depend entirely on 

 a covering of vegetable earth, which, in its forest 

 state, had, for perhaps thousands of years, been 



