“I ought not to omit here to mention, among the causes why ground is improved by producing wood—the minuteness into which its particles are divided by the roots and their fibres. On taking up a young tree, or even a gooseberry bush, and shaking the earth from its roots, we find the mould that falls from it as completely reduced to powder, as if it had been passed through a fine sieve. Now, the fact {316} seems undoubted, that land is much increased in fertility by being brought to this state.” Whether a greater accumulation of vegetable mould or enriching of the soil, would take place under a system of rotation of crops, stirring of the ground, and manuring, or under Nature’s own system of management—whether, under forest, or under the rich leafy grasses depastured by cattle, is a question of the greatest intricacy, and only admits of local decision, being dependent upon climate, soil, and circumstance. From our author’s statements, it would appear that his mind had only ranged along the surface of the subject. He has not taken into account the quantity of root which herbaceous vegetables annually leave in the ground—in some kinds little inferior in bulk to the portion above ground. We have traced oat and wheat roots running down into clay five and six feet (as deep as those of many kinds of trees), extremely numerous, and fine as human hair. He seems not aware that the bulk of yearly vegetable produce is much increased by culture, alternate cropping, and extraneous manure, such as lime, mixture of earths, sea-ware, bones. He has not considered that the annual dead roots within the soil, and the vegetable and animal manure, and the {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 dissipated 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 equable 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, especially of the resinous kinds, and those containing much tannin, if not actually pernicious, have very little fertilizing effect—saw-dust has generally no manuring 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, become richer, and thicken more under pasturage, than under any other common vegetation. This is owing to the manuring of the cattle—to the natural