Agriculture Reference
In-Depth Information
3.3.6 Soil Preparation and Planting
Wheat and barley have similar growth requirements. Typically, soil is prepared by
plowing and disking to form a uniform seedbed. With small grains such as wheat
and barley, the soil must be tilled until it has no clods greater than the size of the
seed. The method used depends on the degree of mechanization of the farmer. In
highly mechanized farms, there may be several implements used to break down
the soil into small fragments. A first will typically be with a plow that turns the
topsoil over and buries weeds. A second and third pass will normally be with a
disk to break up any large clods of soil. Sometimes another pass over the field
will be made with another implement to further reduce the size of unbroken clods.
A mechanical planter will then be used to plant the grains in rows about 20 cm
apart, dropping as many as one seed per centimeter in rows. The actual seeding
rate will vary with variety, distance between rows, rainfall, and the like. In practice,
wheat and barley tend to compensate for over- or underseeding. If there are too few
seedlings for the light, water, and nutrients available, the plants will form more tillers
(stems) and grain heads. Some mechanized farmers in the United States have reduced
tillage to near zero with no-till planters. These machines will open a thin slit in
untilled soil and drop the seed and starter fertilizer. This has the advantage of redu-
cing the number of tillage operations but requires application of herbicides to
kill weeds.
In nonmechanized conditions, the soil is tilled repeatedly to form a smooth
seedbed as seen in Figure 3.17. The seeds are broadcast by hand to obtain a uniform
distribution over the field. The field is then plowed with a stick plow to lightly
cover the seeds. Fertilizer is usually broadcast during tillage operations to be incorpor-
ated into the soil. The resulting stand of plants is random, sometimes tending to form
rows at the spacing of the last pass with the plow. Some farmers may also use animal-
drawn mechanical
planters. This has the advantage of planting in rows to facilitate
hand weeding.
Figure 3.17. Smoothing the seedbed for wheat in India.
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