Environmental Engineering Reference
In-Depth Information
Steps in producing the optimum root zone for turf establishment may
include any or all of: (i) control of existing weeds; (ii) removal of rocks
and rubble; (iii) rough grading; (iv) surface and subsurface drainage;
(v) soil modification; (vi) fertilization and liming; and (vii) final soil
preparation.
Control of Existing, Persistent Weeds
Hard-to-control weeds should be the primary target at this stage. Many
weeds with extensive root systems such as nutsedge (
Cyperus
spp.) are
hard to control after grass has been established, so they should be elim-
inated before establishment. At this stage chemical control with herbi-
cides or soil fumigation are necessary. Non-selective herbicides (see
herbicides in Chapter 11, this volume) such as glyphosate could be
used to eliminate all growing vegetation. Glyphosate virtually eradicates
all plants that come in contact with it. Because it enters the plant only
through leaves or stems, glyphosate does not have residual (long-lasting)
activity in the soil. Some plants may escape the initial application and
require a second application several weeks later. Two other herbicides,
amitrole or delapon are selective. They have little effect on broad-leaved
weeds but can be used to control undesirable grasses. Unlike glyphosate,
amitrole or delapon are taken up through the roots and remain active in
the soil for about 6 weeks, so planting should be delayed beyond that
period. Because weed control with herbicides is most effective when
chemical control is combined with mechanical control, cultivation such
as ploughing or disking should follow shortly afterward.
Much less common but much more effective than herbicides is soil
fumigation with methyl bromide or other chemicals of similar properties.
Fumigation eliminates not only weeds but insects, diseases and nema-
todes as well. Fumigation can be hazardous, so it should be carried out
only by trained and certified professionals. The chemicals used in these
procedures are usually toxic and very dangerous if mishandled. Fumi-
gation is not recommended for residential lawns. It is also expensive and
is therefore seldom used on large areas.
Removal of rocks and rubble
Rocks and rubble should be removed from the soil surface after cultiva-
tion. Unfortunately, contractors occasionally bury construction debris
such as cement, wood and tree stumps. Buried wood eventually decays,
but large pieces of metal or cement could pose an ongoing problem
(Fig. 4.1). If discovered during cultivation, they should be removed.
