nary loam. This is the reason of
the superior fertility of land annually overflowed with water, as Egypt
in the vicinity of the Nile. It is not that the Nile brings down
deposites from the mountains of the Moon, so rich above all that is in
the valleys below. The entire weight of all that a river deposites on
ten acres would not equal in weight the increased vegetation of a single
acre. The cause of the increased fertility is the fact that the deposite
is so fine that it prevents rapid evaporation, and thus causes the soil
to retain moisture for the large growth, and maturity of the plants.

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