Sod
or turf is grass and the part of the soil beneath it held together by the roots,
or a piece of this material.
The term sod may be used to mean turf grown and cut specifically for the
establishment of lawns. However, in British English such material is more
usually known as turf, and the word "sod" is limited mainly to agricultural
senses (for example for turf when ploughed), or avoided altogether, due to the
alternative offensive meaning of the word "sod".
Sod (or turf) for lawns is grown on specialist farms. It is usually grown
locally to avoid long transport and drying out and heat buildup of the product.
It is sold to landscapers, home builders or home owners who use it to establish
a lawn quickly and avoid soil erosion. The farms that produce this grass may
have many varieties of grass grown in one location to best suit the consumer's
use and preference of appearance. It is usually harvested 10 to 18 months after
planting.
On the farm it undergoes fertilization, frequent watering,
frequent mowing and subsequent vacuuming to remove the clippings. It is
harvested using specialized equipment, precision cut to standardized sizes. Sod
is typically harvested in small square slabs, rolled rectangles, or large 4-foot
wide rolls. Some large sod farms may export internationally. Because of the
product's short life after harvest, the sod may be washed clean of the soil down
to the bare roots (or sprigs) which makes shipping lighter and cheaper. Sod can
be used to repair a small area of lawn that has died.
To prevent erosion and damage from sediment and runoff by stabilizing the
soil surface with
permanent vegetation where specific goals might be to provide immediate
vegetative cover
of critical areas, to stabilize disturbed areas with a suitable plant material
that cannot be
established by seed, to stabilize drainage ways, channels, and other areas of
concentrated
flow where flow velocities will not exceed those specified for a grass lining.
Sodding and, for some areas, erosion netting and staples/pegs may be needed for
stabilization.
Use in disturbed areas which require immediate and permanent vegetative cover,
or where
sodding is preferred to other means of grass establishment.
Locations
particularly suited to
stabilization with sod include: waterways and channels carrying intermittent
flow at acceptable
velocities, areas around drop inlets when the drainage area has been stabilized,
residential or commercial lawns and golf courses where prompt use and aesthetics
are important,
and steep critical areas.
Quality turf can be established with either seed or sod; site preparation for
the two methods is similar. The
practice of sodding for soil stabilization eliminates both the seeding and
mulching operations and is a much
more reliable method of producing adequate cover and sediment control; however,
compared to seed, sod is
more difficult to obtain, transport, and store.
Advantages of properly installed sod include immediate erosion and dust control,
nearly year-round establishment
capability, less chance of failure than with seeding, initial freedom from
weeds, and rapid stabilization of
surfaces for traffic areas, channel linings, or critical areas.
Disadvantages - Sod also requires careful handling and is sensitive to transport
and storage conditions. Soil preparation,
installation, and proper maintenance are as important with sod as with seed.
Sod can be laid during times of the year when seeded grasses may fail, provided
there is adequate water
available for irrigation in the early weeks. Irrigation is essential at all
times of the year to install sod. It is
initially more costly to install sod than to plant seed; however, the higher
cost may be justified for specific
applications where sod performs better than seed.
In waterways and channels that carry concentrated flow, properly pegged sod is
preferable to seed because it
provides immediate protection. Drop inlets placed in areas to be grassed can be
protected from sediment by
placing permanent sod strips around the inlet. Sod also maintains the necessary
grade around the inlet.
Because sod is composed of living plants that must receive adequate care, final
grading and soil preparation
should be completed before sod is delivered. If left rolled or stacked, heat can
build up inside the sod thus causing severe damage and loss of costly plant
material.
