sually happens
after the planting of spring crops. A deep and close cultivation of
corn and potato plants after they appear in the row helps to restore
the condition created by the plow and harrow, and often is the best
practice. There is some sacrifice of roots, but the gain far exceeds
the loss. It may be necessary to give a second such cultivation when a
clay soil is deficient in organic matter, but the root-pruning is a
handicap.

Controlling Root-growth.--The exception to the rule that plant-roots
should not be pruned by deep cultivation is found in the case of a
close soil in a wet season. The plants extend their roots only in the
soil at the surface because the ground is soaked with water nearly all
the time. They cannot form far enough below the surface to withstand a
drouth that may follow the wet weather. Good tillage in such a case
demands the pruning of the roots and the airing of the soil when the
ground is dry enough to permit such stirring, and the plants then
extend their roots in the lower soil where they rightly belong.
Judgment is required to decide when such tillage is desirable, but
judgment is needed all the time in farming. When a continued period of
wet weather affects the position of the plant-roots, it rarely is
advisable not to risk deeper tillage than is given in a normal season.
Underdrainage helps to prevent such ill-effect of continued rains in
the early part of a plant's life-time.

Elimination of Competition.--Weeds pump the water out of the soil, use
up available plant-food, and compete for the sunlight. Tillage is given
for several reasons, and one is the destruction of weeds. A weeder
which stirs the soil only an inch or two deep is an excellent destroyer
of weeds when they are starting, but after the weeds are well-rooted,
the weeder acts only as a cultivator for the plants that should be
destroyed. Modern cultivators have fine teeth that let the surface
remain nearly level, and they do their best work when the weeds are
small. The use of "sweeps" should be more general. The blades are so
placed that they slip under the surface, letting the soil fall back so
that a mulch is formed.

Length of Cultivation.--Most tilled crops grow rapidly until they shade
and mulch the soil. Tillage should continue, if possible, until this
occurs. The exception is in the case of orchard trees and other plants
that should not have their period of growth extended late in the fall.
Good tillage tends