Environmental Engineering Reference
In-Depth Information
and each plug is placed in a hole and pressed down, usually with the
planter's foot. Major advantages of plugging are low costs of planting
material and minimal losses. Major disadvantages are high labour inten-
sity and the possibility of weed invasion during the period before the
plugs spread to fill the empty space. Another disadvantage is slow
establishment. Fast-growing cynodon may completely cover the soil
within 4-5 months, but slow-growing zoysia grass may take more than
a year. Unlike seeding or stolonizing, plugging in the tropics is often
accomplished over an extended period of time. Sometimes, because of the
lack of commercial sod or more often because of its high cost, many
residential lawns are gradually established by the continuous transplant-
ing of sod pieces from recently established areas to the new areas. Plug-
ging's multiplication factor, which ideally ranges between 15 and 20 is an
important advantage of this practice. In most cases only 1 m
2
of sod is
needed to produce 5
5-cm plugs for a 15-20-m
2
area. If the size of the
2 cm, as it often is, 1 m
2
of sod can cover as much
plugs is reduced to 2
as 100 m
2
of soil.
Strip sodding
is a modification of plugging. Instead of plugs, strips of
sod are laid in long rows 15-20 cm apart. As in plugging, the bare areas
are filled in by spreading stolons and rhizomes. This method of turf-grass
establishment is somewhat faster, is often performed on larger areas, uses
more plant material, but involves much less manual labour. Zoysia grass
is the species most often established by strip sodding.
Turf Renovation
Sometimes mismanaged turf is in such poor condition that reasonable
improvement is not achievable through routine cultural practices. Some-
times turf-grass species must be changed to match changing conditions,
e.g. on residential lawn progressively shaded by growing trees. In cases
like these, if slopes and grades on the site are adequate and no major soil
modifications are needed, renovation might be considered. Renovation is
the replacement of an existing turf with a new one without most other-
wise essential establishment procedures.
The first step is killing the existing turf and weeds on the area subject
to renovation. This process usually requires a nonselective herbicide such
as glyphosate. Glyphosate is taken up by leaves within several hours and
translocated into roots, rhizomes, stolons, tubers, etc., which it kills
slowly over the next 7-10 days. Some tough weeds, such as nutsedge,
may require an additional application of glyphosate 1 week later. After
the turf area has been sprayed with herbicide, depending upon the
establishment method chosen (seeding or vegetative propagation), sev-
eral alternative steps can be carried out.
