Environmental Engineering Reference
In-Depth Information
Clipping Removal
Under frequent, normal mowing, clippings should be left on the surface
if possible. In tropical climates, grass clippings decompose quickly,
returning so many nutrients to the soil that fertilization needs can be
reduced by as much as 30%. As a general rule, clippings should be
removed only when they interfere with the appearance or purpose of
the turf. For example, on areas such as golf course greens or tees clipping
should be removed routinely; on home lawns they should almost never
be removed. Contrary to common belief, clippings do not increase thatch
build-up. Instead, as a source of easy-to-decompose organic matter, they
contribute to development of humus in the soil. Infiltration of water is
also improved when grass clippings are left in place. Overall returned
clippings play a very positive role in turf grass management.
Clippings should be removed, however, when they are present in
excessive amounts. For example, in the humid tropics, long-lasting mon-
soons sometimes disrupt normal mowing frequency. The large quantities
of clippings that can result should be removed so that they do not
damage the turf by excluding light. For the same reason, clippings should
not be left as undispersed clumps on the turf surface. Many modern
mowers are equipped with blades that either force clipping into the turf
or throw them relatively far, preventing clumping. Alternative methods
are raking, dragging a water-hose over the area and other practices that
disperse clippings.
Mowing Patterns
Frequent and close mowing in the same direction or pattern can impart
grain, a condition in which the turf-grass leaves and shoots lean in the
direction of the cut. On closely mowed turf, such as golf course putting
greens, grain can change the path and speed of a rolling ball and is
therefore highly undesirable. Varying the mowing pattern presses the
turf shoots in different directions with each mowing and tends to make
them grow more upright. In addition to reducing grain, altering the
mowing pattern on closely mowed turfs reduces the excessive wear
that results when the mower is always turned around in the same
locations. Mowing pattern is usually not a concern on turfs mowed
higher, such as parks or home lawns. These turfs, especially when
mowed with rotary mowers, are less likely to develop grain, and even
if they do, their use is generally not affected. Grain is sometimes desir-
able. Sport turf managers use certain mowing patterns to create particular
visual effects. Long strips on athletic fields are often mowed in opposing
directions, which creates streaked or squared patterns. This method is an
