sen the soil, and to undo the
firming that has been taking place while plant roots prevented deep
tillage. At the same time the plow may be used to bury organic matter
below the surface, affording a clean seed-bed. In some soils it has
value in bringing inert soil to the surface, and in mixing the soil
constituents.

Types of Plows.--The kind and condition of the soil, and the character
of the crop, determine the type of plow to be used. A plow with a short
and quite straight moldboard does not bury manure and turf in the
bottom of the furrow so completely as is the case with a long, curved
moldboard. The organic matter should be distributed throughout all the
soil. On the other hand, it is essential to some plants that they have
a fine seed-bed, and one whose surface is free from tufts of grass. The
long moldboard is preferred in breaking a sod for corn. Its use in
plowing for all crops is more general than it should be, the gain in
pulverization of the furrow-slice, due to the curve, and the neatness
in appearance of the plowed land, inducing its use.

The disk plow has been used chiefly in soils not requiring deep
plowing. It pulverizes better than a moldboard plow, and buries trash
more easily.

[Illustration: Deep tillage.]

The device for using two disks to turn a single furrow-slice rests upon
a sound principle. This plow may be set to run deeper than moldboard
plows go, and it mixes well all the soil that it turns. The disks are
so hung that the mixing of all the soil to a depth of twelve or fifteen
inches is admirable. The deep-tilling plow does not bury the organic
matter in the bottom of the furrow, and thereby permits the deepening
of the soil without bringing an undue amount of subsoil to the surface.

Subsoiling.--The theory of subsoiling always has been captivating. Most
soils are too shallow, inviting injury from drouth. Enthusiasm
regarding subsoiling comes to large numbers of farmers at some time in
their experience, and a great number of subsoil plows have been bought.
The check to enthusiasm is the fact that few men ever have seen such a
plow worn out. Some reasons are as follow:

(_a_) The subsoil at time of spring-plowing rarely is dry enough
for good results, and there is danger of puddling; (_b_) the
subsoil often is too dry and hard in late summer, when rains permit
easy breaking of the top soil for fall grain; (_c_) the work
doubles the labor and time of plowing, and