CRUrCKSHANK'S PRACTICAL PLANTER. 317 



sward and the stubble ploughed down, conduce much 

 more to enrich and thicken the soil than the tree 

 leaves, blown about by the winds, and nearly dissipa- 

 ted into air, before the residuum fixes as a part of the 

 soil ; and also that ploughing is often beneficial to 

 shallow soils, by mixing the thin covering of mould 

 with the pure earth of the subsoil, — the vegetable soil- 

 matter, from consequent deeper cover, and more equa- 

 ble moisture, not losing so much by evaporation, and 

 at the same time being more efficacious as nutriment 

 to the vegetation. He seems unacquainted with the 

 fact, that the matter of wood and tree-leaves, espe- 

 cially of the resinous kinds, and those containing 

 much tannin, if not actually pernicious, have very lit- 

 tle fertilizing effect — saw-dust has generally no ma- 

 nuring influence, but turns into peat. He also appears 

 to be ignorant, that some kinds of vegetables draw 

 more from the air and water, and others more from 

 the earth ; and, especially, that vegetables in a moist 

 climate, depastured or cut before maturity, exhaust 

 the soil much less than when allowed to seed. In 

 Britain, soils, particularly those of good quality, be- 

 come richer, and thicken more under pasturage, than 

 under any other common vegetation. This is owing 

 to the manuring of the cattle— to the natural grasses 

 not being what is termed scoiu-ging plants, especially 



