The First Book of Farming | Page 7

the first question, "In what part of the soil are most of the roots?"
you will give the following answers: "In the upper layer." "In the
surface soil." "In the softer soil." "In the darker soil." "In the plowed
soil."
These are all correct, but the last is the important one. Most of the roots
will be formed in that part of the soil that has been plowed or spaded.
The second question, "How deep do the roots penetrate the soil?" is
easily answered. Roots will be found penetrating the soil to depths of
from two to six feet or more. (See Fig. 8.) The author has traced the
roots of cowpea and soy bean plants to depths of five and six feet, corn
roots four and five feet, parsnips over six feet. The sweet-potato roots
illustrated in Fig. 8 penetrated the soil to a depth of over five feet. The
roots of alfalfa or lucern have been traced to depths of from thirteen to
sixteen feet or more.
How near to the surface of the soil do you find roots? Main side or
lateral roots will be found within two or three inches of the surface, and

little rootlets from these will be found reaching up as near the surface
as there is a supply of moisture. After a continued period of wet
weather, if the soil has not been disturbed, roots will be found coming
to the very surface and even running along the top of the soil.
As to the fourth question, How far do roots reach out sidewise or
laterally from the plant? you will find roots extending three, four, five
and even six or more feet from the plant. They have numerous branches
and rootlets, which fill all parts of the upper soil. Tree roots have been
found thirty or forty feet in length.
We started on this observation lesson to find out something about the
habit of growth of roots, so that we could tell how the roots do their
work for the plant. But before going on with that question, let us stop
right here and see whether we cannot find some very important lessons
for the farmer and plant grower from what we have already seen. Is a
knowledge of these facts we have learned about roots of any value to
the farmer? Let us examine each case and see.
Of what value is it to the farmer to know that the larger part of the roots
of farm plants develop in that part of the soil that has been plowed or
spaded? It tells him that plowing tends to bring about the soil
conditions which are favorable to the growth and development of roots.
Therefore, the deeper he plows, the deeper is the body of the soil
having conditions best suited for root growth, and the larger will be the
crop which grows above the soil.
Of what value is it to the farmer to know that the roots of farm plants
penetrate to depths of five or six feet in the soil? To answer this
question it will be necessary for us to know something of the conditions
necessary for root growth. So we will leave this till later.
Of what value is it to the farmer to know that many of the roots of his
farm plants come very near the surface of the soil? It tells him that he
should be careful in cultivating his crop to injure as few of these roots
as possible. In some parts of the country, particularly in the South, the
tool commonly used for field cultivation is a small plow. This is run
alongside of the row, throwing the soil from the crop, and then again

throwing the soil to the crop. Suppose we investigate, and see how this
affects the roots of the crop.
[Illustration: FIG. 8. Sweet potato roots. The great mass of the roots is
in the plowed soil. Many of them reach out 5 to 7 feet from the plant.
Some reach a depth of more than 5 feet, and others come to the very
surface of the soil.]
[Illustration: FIG. 9. Soy-bean roots showing location, extent and depth
of root-growth.]
Let us visit a field where some farmer is working a crop with a plow, or
get him to do it, for the sake of the lesson. We will ask him to stop the
plow somewhere opposite a plant, then we will dig a hole a little to one
side of the plow and wash away the soil from over the plow (see Fig.
10), and see where the roots are. We will find that the plow-point runs
under many strong-feeding lateral roots and tears them off, thus
checking the feeding power of the plant, and consequently checking its