Environmental Engineering Reference
In-Depth Information
Irrigation systems installed on greens are usually underground,
remote-controlled systems with rotary pop-up sprinkler heads. Gener-
ously budgeted golf courses use sprinkler systems in which each indi-
vidual head can be controlled by a centrally located computer attached to
a weather station. If such an irrigation system is not available, the turf
manager must make water-scheduling decisions on the basis of readings
from moisture-sensing devices, observation of the turf and professional
experience.
Greens should be watered only to the depth of the upper sand layer.
Irrigation should be scheduled to replace the water used by the turf when
approximately one-half of that water has been used. Because water
retention and water use will differ in different areas, the manager must
closely and frequently observe the results and make necessary adjust-
ments. Setting the irrigation programme 'once and forever' will not be
sufficient.
Cultivation and thatch control
Relieving compaction, improving water infiltration and percolation, con-
trolling grain and thatch, and providing a smooth, uniform putting
surface may require several cultivation operations, which were discussed
in detail in Chapter 8. Here, only those modifications that apply specif-
ically to cultivation of putting greens will be addressed.
A limited thatch accumulation of 5-7 mm increases wear tolerance,
reduces soil compaction, and overall may be desirable for putting greens.
Excessive thatch may cause mower scalping, reduced green speed, in-
creased disease occurrence, development of hydrophobic areas and
restricted water infiltration. Because thatch accumulates when its growth
exceeds the rate of its decomposition, growth-stimulating practices
should be minimized. Moderate nitrogen fertilization, supplemented
with iron (which provides better colour), and use of slow-release nitrogen
sources usually reduce rates of growth and thatch accumulation on
greens. Maintaining good soil air - water relationships provides favour-
able conditions for microbial activity and also prevents thatch accumu-
lation. Mechanical methods of thatch control are usually used routinely
on sand-based greens and less frequently on natural greens. A thatch
layer over 2.5 cm may require severe measures such as deep vertical
mowing, frequent deep coring, or in extreme cases, stripping of the entire
sod from the green and establishment of new turf.
Top-dressing is used on greens to control thatch, smooth the surface
and control grain. On USDA greens, the top-dressing material is usually
pure sand; on natural greens, soil or sand is used. As always the top-
dressing material must be at least as coarse as the underlying soil.
