40 FOREST PLANTING. 



cases the soil should be brought, by proper plowing and 

 subsoiling, into such a condition that plants will grow 

 there. The soil having been deeply broken and mixed 

 up with the macerated hard pan brings the hidden treas- 

 ures of the deeper soil, consisting of easily soluble salts, 

 carbonates or oxides, in contact with the fertilizing power 

 of light and air, thus restoring the plant-food that had 

 been washed down into the all-absorbing subsoil. Be- 

 sides this the deep and thorough pulverizing of the 

 impoverished soil increases the depth of the ground to 

 which gases and humidity from the open air may pene- 

 trate, helping the growth of plants by increasing the 

 warmth of the soil, and thus giving a more regular 

 moisture to the roots of plants, both by supplying it in 

 times of drouth and by carrying it away when in excess. 

 Deep plowing of the ground is unavoidably necessary, 

 if it is intended to plant forest trees with long tap-roots 

 on heavy compact soil, as these trees will never have a 

 vigorous growth, unless the soil is rendered fine to a con- 

 siderable depth. 



On heaths deep cultivation destroys the growth of 

 lichens and breaks up the hard pans, both of which are 

 heavy drawbacks to forest planting on the infertile 

 heaths. The carbonaceous soil is entirely insoluble and 

 impenetrable. It can ocly be rendered fertile by break- 

 ing and mixing it with the other ingredients. 



The same favorable effect is accomplished with peat or 

 muck soils. Stirring them up thoroughly to the depth 

 of about 12 to 14 inches renders them able to produce 

 valuable forest trees. 



Forest vegetation cannot succeed but on soil which 

 contains sand, clay and lime, the two first named being 

 the most potent factors of vegetable growth. If the soil 

 does not contain at least some parts of each of the three 

 named minerals, complete infertility will be the result. 

 The more equally these three ingredients are mixed 



