can keep track of each other's work. We must make our plans, too, on
paper, which will help out. We have catalogues to write for, garden
stakes to make, and no end of things will come up. But first you boys
ought to understand a bit more than you do about the soil. It is a
storehouse of good things. Knowledge of the soil is a key to this
storehouse.

"We can roughly divide the soil into three classes and call these sand,
clay, and humus. The ideal soil has all three of these elements in it.
Sandy soil is made up, as the name itself really tells, of broken up
rock masses. One can tell this sort of soil by its lightness and the
ease with which a mass of it drops apart. By the word lightness one does
not mean colour or weight, but looseness. A clay soil may be told by its
stickiness; its power to form lumps or masses; its tendency to crack and
bake under the hot sun. Such a soil is called heavy. Humus soil is made
up largely of decayed animal and vegetable matter. Its presence is told
by a dark, rich colour.

"In trying to improve the soil we are dealing with, we have first to
think of its physical, and second, its chemical condition.

"The great needs of the soil are air and water. Just think of all soils
as made up of many particles; let us say like a lot of marbles, one
placed upon another. Each given mass of particles has a given air space
between every particle. Again, if a marble is dipped in water a film of
water remains on it a short time. Let us think of the particles as
always having a film of water on them. Then, as roots and root-hairs of
plants strike down among these they find the two necessities, air and
water.