One more evidence is found on our sandy pine plains. Our common forest-trees, as beech, maple, elm, or linden, will not flourish there. Such land will produce comparatively no corn, oats, or wheat. But rye that stands drought better than any other grain, grows tolerably well. But such plains always produce an enormous growth of pine timber, hardly equalled in the number of cords to the acre, by the heaviest-timbered land of the river bottoms. Why is this? Does a maple need so much more food than a pine, or is it in the habits of the trees? It is not in the richness or poverty of the soil, but in the adaptation of the trees to reach and appropriate moisture. The roots of the maple and beech, spread out near the surface of the ground. And it being a light, porous, sandy soil, it does not retain moisture enough to promote their growth. But whoever notices a pine-tree that has been turned up from the roots by the wind, will see that the roots run down almost perpendicularly ten or fifteen feet into the sand. There they find plenty of moisture and hence their great growth. This principle explains the comparative productiveness of all soils. A soil composed of light muck, or a kind of peet-soil, will dry up soon. There is nothing to prevent rapid evaporation; hence it is always unproductive, for want of suitable moisture. Mix with it clay, to render its texture more firm, and it will retain the moisture, and be very productive. Clay alone is too solid to retain moisture; it runs off, as from a brick. Mix sand with it, and it becomes mellow, and retains moisture, and produces great growth. Sand allows so free and rapid an evaporation that it is unproductive. We say it leaches and is hungry, and so it is, because it has little power to retain water. Our manures do it good, only as they are calculated to aid it in controlling moisture. If we apply a light manure as we would to clay, it is comparatively useless; it adds no firmness to the texture of the soil, and hence does not increase its capacity for controlling water. On such land, the only good that manure does, is while decomposition is taking place in the soil, it renders it more moist, and hence more productive. Apply clay to such a soil, and it will increase its firmness and consequent capacity of retaining and appropriating moisture, and thus render it highly valuable. Dry straw manure is sometimes said to dry up land, and ruin crops. So of turf in a dry season. In a wet season they greatly increase the growth of crops. Now they contain just as much food for plants in one season as another. Hence a soil too easily impervious to the atmosphere, will be a poor soil, that is, will produce poorly, simply because it has no power to retain the necessary moisture.