HARROWING AND ROLLING
HARROWING
After spading or plowing the next operation in the preparation of the
soil is generally raking, harrowing or dragging. The objects of these
operations are:
To break lumps and clods left by the plow and spade and to further
pulverize the soil.
Harrowing and raking aid in controlling soil ventilation, and put the
soil in better condition to absorb moisture.
They check the loss of moisture by making a mulch of fine loose earth
on the surface.
The harrow and rake destroy the weeds.
The harrow brings about conditions favorable to the even distribution
of seeds.
It is also the tool generally used to cover seeds sown broadcast.
Harrowing is generally done just before planting, and with some crops
just after, to cover seeds or to smooth the ground. Harrowing is also
done in the first stages of growth of some crops to kill weeds and
make a soil mulch. The harrow should always follow the plow within a
few hours unless it is desired to leave the land in a bare fall or
winter fallow. At other times of the year the lumps of earth are apt
to dry out and become hard and difficult to break. If there is but one
work team on the farm it is a good plan during the plowing season to
stop the plow in time to harrow the day's plowing before the day's
work ends.
HARROWS
There are several types of harrows in use. They may be classified
according to the style of their teeth or cutting parts; they are as
follows:
Rolling cutter harrows.
Spring-toothed harrows.
Spike-toothed harrows.
Coulter-toothed harrows.
Chain harrows.
Brush harrows.
Plank or drag harrows.
These types vary in the depth to which they cut, and the degree to
which they pulverize the soil.
_Rolling cutter harrows._ Harrows of this type (see Fig. 54) consist
of one or more revolving shafts on which are arranged a number of
concave disks. These disks are either entire, notched, or made of
several pieces fastened together. Examples of these are the disk,
cutaway and spading harrows. These harrows cut and move the soil
deeper than the other types. They are especially adapted to work on
heavy clay soils.
The value of this type of harrow as moisture preservers depends on the
manner in which they are used. If the disks are so set that they cover
but a portion of the surface with a mulch of fine earth they leave a
ridge exposed to the action of the wind and sun and the rate of
evaporation is greatly increased. The disks should be set at such an
angle that the whole surface shall be stirred or covered. Soils which
need the disk harrow should generally be gone over again with some
shallower working tool to smooth the surface. An objection to the
rolling cutters is that unless great care is taken they will leave the
land in ridges and valleys.
The two gangs of disks throw the earth in opposite directions. They
are generally set to throw it from the centre and the result is a
shallow double furrow the width of the machine. By lapping each time
the furrow is partially filled, but to get the land smooth a smoothing
harrow should be used after the rolling cutter.
_Spring-toothed harrows_ (Fig. 55). Spring-toothed harrows with their
curved spring teeth enter the soil readily, draw moderately easy and
pass over obstructions without much difficulty. They are very useful
in new land that is full of roots and stumps and also stony land. They
pulverize the soil to an average depth. They leave the soil in ridges.
The ridges can be leveled by a smoother in the shape of a piece of
plank attached to the rear of the harrow. On newly plowed grass land
they tend to tear up the sod and leave it on the surface. They also
tend to drag out coarse manures when plowed in.
The original and more common form of the spring-toothed harrow is a
floating harrow when at work. That is, it rests on the points of the
teeth and is dragged or floated over the ground. A newer form of
spring-toothed harrow, sometimes called the fallow cultivator, is
mounted on high wheels and its action is largely controlled by them.
This form of harrow is claimed to do much better work than the
floating harrow and may in a large measure displace the rolling
cutter. The weight of this harrow is entirely taken from the soil
except in the wheel tracks, and the entire action is that of
pulverizing and lightening the soil.
_Spike-toothed harrows_ (Fig. 56). The teeth of these harrows are
round, square or diamond-shaped spikes fastened into a wood or iron
frame. The teeth are set in a vertical position or are inclined to the
rear. These harrows are shallow in their action; they run easily but
tend to compact the soil more than the other types and are therefore
better adapted to loose soils and to finishing off after the work of
the deep cutting harrows. They are also used for covering seeds.
[Illustration: FIG. 56.--SPIKE-TOOTHED HARROWS.]
[Illustration: FIG. 57.--A COULTER-TOOTHED HARROW.]
[Illustration: FIG. 58.--A PLANK HARROW.]
_Coulter-toothed harrows._ The coulter-toothed harrows (Fig. 57) have
teeth resembling the coulter of a plow twisted or bent into various
shapes. The Acme is a good example of this class of harrow. It cuts,
turns and pulverizes the surface soil somewhat after the manner of the
plow. It prepares a fine mulch and leaves an excellent seed bed. It
is an excellent harrow to finish off with after using a rolling
cutter.
_Chain harrows._ The chain harrow consists of a web of chains linked
together. They have a wonderful power for breaking clods and are
useful for collecting weeds. They shake the dirt from the weeds and
roll them into heaps. Chain harrows tend to compact the soil.
_Brush harrows._ The brush harrow is a primitive form made by
fastening brush to a long pole. Brush harrows are quite useful for
brushing in seed and for pulverizing manure broadcasted on grass
lands.
_Plank harrows._ The plank harrow (see Fig. 58) is made of several
planks fastened together so that each plank overlaps the next one to
it, like the clapboards of a house. This harrow is as good as a roller
in fining and smoothing the surface soil. It is an excellent tool to
use alternately with a spike or coulter-toothed harrow on lumpy soil.
This tool rasps or grinds many of the lumps or clods which slip by the
harrow teeth and presses others into the ground so that the harrow
following can get a grip on them. It is a harrow that can be made on
any farm. This planker is an excellent tool to smooth the surface, for
broadcasting small seeds and for planting truck crops.
ROLLING
The objects of rolling are:
To compress the surface soil so that the harrow will do its work more
efficiently, also to break clods or lumps that may have resisted the
action of the harrow.
To smooth the surface of the soil for an even distribution of small
seeds, and to firm the soil around such seeds after they are planted
so that they will keep moist and sprout readily.
To give compactness to soils that are light and loose and thus enable
them to hold moisture and plant food better.
To press into the ground the roots of plants partly dislodged by the
frost.
To remove the conditions favorable to the development of many kinds of
insects.
To sink surface stones so that they will not interfere with harvesting
the crop.
Light porous soils may be rolled at any time, but clay soils can be
rolled to advantage only when they are stiff and cloddy.
Spring-sown grain is often rolled as soon as sown. This is all right
in ordinary spring weather, but if showers are frequent and the soil
is quite moist the rolling should be omitted till after the grain is
up. The same practice will apply to autumn-sown grain also. If the
soil is dry the rolling helps it to pump water up to the seeds. But if
it is moist and showers are frequent the combined action of the
roller and the rain is to make so thick a crust that many of the seeds
will not be able to force their way through it or will be smothered by
poor ventilation. After the grain is up the rolling may be done to
advantage, as it then makes a firm soil about the roots of the plants,
a condition of benefit to grain crops.
The most simple form of roller is a solid or hollow cylinder of wood
fastened into a frame by which it is drawn. Some rollers have spikes
or blunt attachments fastened to their surfaces for breaking clods. A
roller that is quite popular consists of a cylinder of pressed steel.