Environmental Engineering Reference
In-Depth Information
Fig. 6.1. Early mower used around 1900.
which unwanted pathogens or other organisms can enter the plant.
Removal of leaf area reduces the plant's capacity to carry out photosyn-
thesis and consequently lowers production of carbohydrates. Reduced
production of carbohydrates results in decreased production of new
roots, which in turn results in decreased abilities to draw water and
nutrients from the soil. All these negative factors would seem to indicate
that grasses should be mowed as infrequently as possible, and that
conclusion is correct for over 10,000 species of wild and forage grasses
around the world, but the 40-50 species of the so-called turf-grasses are
different. They have the unique ability to compensate for the loss of leaf
tissue to mowing by increasing their density below the mowing height.
For these species and varieties mowing is still somewhat stressful, but it
is not damaging if constant mowing height is maintained. The proper
mowing height and frequency are those that provide the optimal balance
between desired appearance of the turf and the physiological abilities of
turf-grasses to withstand mowing stress. Much scientific research has
been conducted to determine this balance not only for each turf-grass
species but also for each turf-grass variety. Even occasional mowing
below the point where stems branch is tremendously stressful, so remov-
ing only a modest portion of the leaves and keeping consistent mowing
height are crucial.
Mowing Height
The height to which a given grass can be mowed is directly related to its
ability to produce enough leaves and to keep up with production of
carbohydrates. This ability is determined by the growth habit and type
of the grass. Factors such as the length of internodes, the number of
stolons or rhizomes, the height of the crown above the soil surface and
natural vigour all influence the amount of leaf mass produced by a
