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Several sport turf
managers have inquired about proper
mowing heights since their coaches
requested lower mowing, usually to speed
up the field. To answer this I give
three basic mowing rules and then ask a
lot of questions. Here are a few general
mowing rules and actual examples from
your fellow sports turf managers to show
how mowing strategies need to change to
fit specific needs:
In general the one third mowing rule
suggests that you should not remove more
than one third of the existing leaf
canopy at each mowing, i.e., for a mower
set at 2 inches mow when the grass gets
to a height of 3 inches to provide a
1-inch clipping. The 1/3 rule was based
on canopy removal studies that noted a
decrease in rooting when more than 1/3
of the leaf volume was removed in a
single event. It is interesting to note
that the 1/3 rule was based on research
using leaf volume and that for ease of
interpretation it has evolved into a
measure based on 1/3 of the mowing
height. Either way the 1/3 rule is a
good standard that reduces turfgrass
scalping and root loss, yet it says
nothing about mowing height strategy.
Taller mowing provides deeper roots.
This rule is quite true and it has
particular importance when dealing with
heat and drought stress, especially in
limited or non-irrigated situations. A
taller mowing height provides canopy
shade to cool the surface and deeper
roots to survive drought. In
non-irrigated situations raising the
mowing height is advisable to survive
summer stress.
In contrast, those with irrigation would
be advised to maintain a consistent
mowing height throughout all seasons.
Raising the mowing height may have
benefits but it also produces fewer
shoots and less density. Within reason
and as a rule, shorter mowing increases
shoot density and provides a better
biomass-mat barrier to keep players from
contacting the soil. Shorter mowing
usually requires more frequent mowing.
If water is not limited then it is
better to consistently train the grass
for maximum density with shorter mowing
rather than reducing density in the
summer with taller mowing and then lower
the mowing height just before autumn
football.
Because leaf growth changes with
fertilizer, water, and seasonal
temperature I first fix the mowing
height to match the sport, coach’s
expectations, and player ability. After
agreeing on the height, and that’s not
always an easy task, develop a routine
mowing frequency that does not violate
the 1/3 rule and add some of your own
ideas to make the field shine; here’s
how some of you have done it.
Northwestern University, Chicago,
sand-based Kentucky bluegrass football
field. Jeff Salmond, CSFM, has a
strategy of maximizing turfgrass density
and surface mat to prevent breakthrough
and exposure of unstable sand. This
field is typical of a high-end
professional or college field. Jeff mows
with a Toro triplex 2600 fairway mower
and he is hoping to purchase the
Sidewinder version so that he can
side-shift the mower units and avoid
wheel tracking when mowing yard line
stripes. He mows Monday, Wednesday, and
Friday without collecting clippings to
keep up with the 1/3 rule. His mowing
height varies between 1 3/8 to 1 1/2
inch from August through mid-October,
and 1 1/4 inch at all other times.
He lowers the mowing height halfway
through the autumn football season
because the grass has worn some and
slowed due to cold temperature. Lower
mowing allows for some grass removal and
a cleaner surface. From early spring
through summer Jeff keeps the mowing
height lower. “I like to train the grass
for maximum density and keep it from
getting too leafy and stringy. Once
we’ve made the density during the spring
and summer we raise the height back to
the 1 3/8 to 1 1/2 range for the first
half of the football season,” he says.
This “new school” strategy is a good
example of adapting old mowing rules
into a sound strategy to fit the sport
and coaches’ desires. The “old school
strategy” would have been to raise the
mowing height during the summer to avoid
stress and lower it in the fall for the
football season. Since drought is not a
factor in this situation, Jeff options
for the frequent and shorter mowing rule
that maximizes turf density.
John Netwal has a different mowing
strategy for the STMA Soccer Field of
the Year from North-Scott, IA. John’s
sand-based high school soccer field is
always mowed at 5/8 inch with a National
Triplex reel mower. His mowing frequency
can range from daily to every 3 days
depending on rate of growth.
“We use Primo to regulate growth, reduce
the amount of clippings, and produce a
thicker turf . . . without the Primo we
would never be able to keep up with the
mowing on our budget,” he says. “Because
the clippings are so small we can keep
the mowing height low and still operate
the mower faster which cuts down our
mowing time.”
This quality of mowing is not usually
found at the high school level, but John
has been one the leaders in bringing new
rules to the old school. John has even
been letting the football team use the
soccer field for special events, now
there’s a switch.
I haven’t forgot about you cool cats in
the warm climate. Luke Yoder, Director
of Field & Landscape Maintenance at San
Diego’s PETCO Park, showed me something
I had never seen before and that was a
baseball field with the infield mowed
taller than the outfield.
“The Bull’s-Eye Bermudagrass on this new
field was first mowed at 7/8 inch but
the surface was too slow for the
Padres.” After a season of fine tuning
here’s how Luke and the Padres play it:
The game condition mowing height for the
outfield is a 1/2 inch and the infield
is 3/4 inch. At 3/4 inch the outfield
was too tall and players complained of
hanging up cleats in the surface that
was too slow and soft for their level of
ability. Luke altered the mowing
strategy to remedy the surface without
damaging the grass, in fact, he says the
aggressive Bulls-Eye prefers it that
way.
“They needed a faster and firmer surface
that didn’t hang up cleats. To get that
we needed to drop the mowing height to
1/2 inch.” He goes on to explain “mowing
the aggressive Bermudagrass constantly
at the same height allows the grass to
get puffy and scalping occurs that makes
the surface uneven and unsightly, so
when the team is away for 7 days we drop
the mowing height of the outfield to
3/8-inch and the infield to 1/2 inch.”
They do this for 3 days to scalp off the
puffy top of the Bermudagrass and allow
new growth from below. “We raise the
height back up to normal 4 days before
they return. For a 14-day road trip we
also have time to do some verticutting
and topdressing.”
Jeff Salmond, John Netwal, and Luke
Yoder are three of your fellow sports
turf managers that will be at the 2005
STMA gathering in Phoenix and they will
be able to give you a first hand account
of their mowing strategies.
Umpires and officials enforce rules of
the game. Coaches, players, and athletic
directors often influence the playing
height of the field. But don’t you ever
forget that Mother Nature is the judge
of all rules. Mow too short or too tall,
not often enough or not at all, and she
will make you pay with green you can’t
afford. These three wise men have
figured it out.
Questions? Send them
to Dave Minner at Iowa State University,
106 Horticulture Hall, Ames, IA 50011,
or email
dminner@iastate.edu. Or, send them
to Grady Miller at the University of
Florida, PO Box 110670, Gainesville, FL
32611, or email
gmiller@mail.ifas.ufl.edu. |