ARBORICULTURE. 355 



or siliceous, sandy moor lands, it generally consists of the heath 

 soil in a compact layer about an inch thick, containing a large 

 proportion of oxide of iron, and impervious to water. Beneath, 

 and next to this, is generally gray or white sand, surcharged with 

 water ; and whenever trees are planted, by the slit mode, on soils 

 so constituted, they never make any healthy growth, but perish 

 so soon as the roots reach the hardened stratum : trenching, or 

 the furrow plough must be employed in such cases to destroy the 

 impervious stratum, and render free the circulation of water and 

 air, otherwise the attempt to establish trees will be vain. When 

 the land is clean, friable, moderately deep, free from, and not 

 retentive of stagnant moisture, the mode of planting by holing 

 may be adopted with propriety. Lands of a tenacious, clayey 

 nature, and also those of the best quality, employed for forest 

 planting, ought to be trenched, as being the most economical ulti- 

 mately, and the most effectual, for these kinds of soil. 



The principle on which manure is objected to for the rearing 

 of forest trees, is., that it will force the growth of the tree beyond 

 its natural state, and render the deposit of .vegetable fibre soft, 

 and of diminished strength and durability. This, however, is 

 carrying the point to an extreme to which it is never likely to be 

 in the power of any planter to arrive, were he even willing to at- 

 tempt it. To manure a poor soil, for it should be here kept in 

 view that this and not a rich, or even moderately rich soil, is 

 intended, can have but one effect, and that is to improve the 

 growth of the trees. But the great, immediate, and important 

 object of manure here, is to furnish a liberal supply of food while 

 the plant is in its first stages of growth, thereby giving it the 

 means to form a strong constitution, enlarging its number of roots 

 and rootlets, and, at the same time, improving the quality of the 

 exhalations from the soil, for absorption by the leaves, which is, 

 in fact, a melioration of the local climate or air. All these im- 

 portant points to the health of the tree, to the value of its timber, 

 and to the attainment of the object in view, a valuable return in 

 the shortest space of time for the capital expended, are thus 

 highly promoted, and, in a great measure, secured by trenching, 



