Irrigation
Correctly irrigating is always a
high priority when maintaining turfgrass plantings, but
is particularly important when grasscycling. Applying
too much water is wasteful and can increase growth, requiring
more frequent mowing. Not applying enough water may lead
to unhealthy, slow-growing grass vulnerable to disease
and insect pests. In general, deep irrigation leads to
deep root systems, which increases drought resistance
and reduces stress.
Turfgrasses vary in their need for water. Warm-season
turfgrass (bermudagrass, zoysiagrass, buffalograss, and
St. Augustinegrass) are more drought resistant than cool-season
turfgrasses (tall fescue, bluegrass, annual and perennial
ryegrass) and require about 20 percent less water.
Table 2 indicates
how many minutes to irrigate warm and cool season turfgrasses
each week, based on the precipitation rate of the irrigation
system. If runoff or brown spots occur with one weekly
irrigation, the weekly total should be divided by two,
three, or four, to water two, three, or four times a week
for fewer minutes. Irrigating until runoff just begins
is the preferred length of an individual irrigation. In
cases where soil has a slow infiltration rate or the irrigation
precipitation rate is high, water cycling is necessary.
To accomplish cycling effectively, irrigate until runoff
just begins, turn the system off, and repeat the process
in ten or fifteen minutes before the soil surface dries
out. Repeat if necessary.
To determine the precipitation rate, conduct 'can tests'
by setting out small, empty straight-sided containers
every ten to fifteen between sprinkler heads irrigated
by the same valve, and run the system for fifteen minutes.
There are a wide array of cans that work well for this
purpose, including clean empty tuna and cat food cans.
(If cups or other non-straight sided cans are used, volumetric
measurements need to be taken, which increases the amount
of time required for this task.)
Measure the amount of water in each can with a ruler,
and determine the average amount of water per can. Multiply
this average by four to determine the precipitation rate
per hour. Conducting 'can tests' regularly is useful for
determining how evenly irrigation water is distributed
over the area (distribution uniformity), allowing sprinkler
head misalignments and other mechanical problems to be
corrected. The best time to irrigate is early in the morning,
because less water is lost to evaporation, and water pressure
is at its peak. Irrigating in the afternoon is wasteful
due to high evaporation rates, and prolonged damp conditions
in the evening may encourage disease development.
