Environmental Engineering Reference
In-Depth Information
turf-grass seedlings may cause fear that turf establishment is failing.
In addition, at this stage herbicides should not be used because the
young grass seedlings are too sensitive to tolerate them and may sustain
severe injury. Fortunately, appearance of the newly seeded turf greatly
improves after the first mowing and keeps improving with time. Mowing
at the correct height removes the growing points of most weeds without
harming the crowns of the turf-grass plants, and in many cases compe-
tition from strong turf-grasses weakens weeds, so herbicides may not be
needed at all. Cynodon is an exception; in the humid tropics, it is usually
not sufficiently competitive and requires herbicides for control of both
grassy and broad-leaf weeds. Herbicides such as 2,4D, MCPA, dicamba
and MSMA can be quite safely applied after 4-5 weeks (see Chapter 11,
this volume).
Vegetative Establishment
Sodding
Sod is established turf that is harvested, with roots and soil attached to it,
and transplanted from its place of origin and installed like carpeting to
grow in another place. Sod is usually produced on a farm that specializes
in commercial production of turf-grass. Sodding is the most expensive
method of turf establishment but produces an established turf within
hours rather than weeks or months. Almost all warm-season turf-grasses
can be sodded, but zoysia grass, St Augustine grass and centipede grass
are established in this way most often. The only disadvantage of sod is its
high cost. Otherwise it provides an instant turf, which requires no extra
maintenance other than daily watering during the early weeks of estab-
lishment.
After being harvested at the farm, sod is brought to the site in the
form of rectangular pieces or as long rolled strips. Properly harvested sod
is delivered to the site with a thin layer of soil. The general rule is to
harvest a layer of sod as thin as it can be cut and still hold together. For
most species, that means about 2-cm thick. After being cut, the sod
should be moved immediately to its destination and laid as soon as
possible. Sod that has been stacked and left for several days usually
dries out and often turns yellow or a pale green colour. In tropical
climates, stored sod loses its vigour after 2-3 days. After 5-6 days stock-
piled sod is usually of very little value, even if watered.
Sod should be laid in a bricklike pattern, such that the corners of four
pieces never come together at one place (Fig. 4.9). Gaps between pieces
should be as small as possible to prevent invasion by weeds. On hills sod
should always be laid perpendicular to the slope. Where the slope is
