reat 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 growth. Now, if we can get a cultivator, we will have
that run along the row and then wash away the loosened soil. It will
be found that few, if any, of the main lateral roots have been
injured.

Is it of any value to the farmer to know that roots extend laterally
three to six feet and more on all sides of the plant, and that every
part of the upper soil is filled with their branches and rootlets?
This fact has a bearing on the application of manures and fertilizers.
It tells the farmer that when he applies the manure and fertilizers to
the soil he should mix the most of them thoroughly all through the
soil, placing only a little directly in the row to start the young
plant.

To find out how quickly the roots reach out into the soil, wash the
soil away from some seedlings that have been growing only a few days,
say, seven, ten and fifteen. (See Fig. 11.)

From our observations, then, we have learned the important lessons of
deep, thorough plowing, careful shallow after-cultivation, and that
fertilizers should be well mixed with the soil.

We are now ready to go back to our study of the habit of growth of
roots, and can perhaps tell something of how the root does its work
for the plant.

It is very easy to see how the roots hold the plant firmly in place,
for they penetrate so thoroughly every part of the soil, and to such
distances, that they hold with a grip that makes it impossible to
remove the plant from the soil without tearing it free from the roots.

It is also on account of this very thorough reaching out through the
soil that the roots are able to supply the plant with sufficient
moisture and food.

We have doubtless observed that most of