TURF WATERING

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TURF WATERING
Edited by Vincent Mannino, County Extension
Director Texas AgriLife Extension Service
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Watering your lawn seems like a simple task, yet
there is more to it in Texas!

• It is about
• Knowing about how much water is needed
• Producing a healthy grass that can persist on
  the least amount of irrigation water
• Knowing how to water your lawn efficiently for
  the good of the lawn
• Keeping applied water on your landscape by
  avoiding misapplication and runoff which can
  carry sediment, nutrients and pesticides AND
  wastes water!

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Average Annual Rainfall
10
20
40
30
50
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Rainfall lessens as you go west. Irrigation
requirement is greater in west Texas for the same
grass one would grow in East Texas (Bermuda grass)
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What do I need to know about my lawn and how does
that influence how I water?
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Most homeowners ask

1. What do I need to know about my lawn (soil type,
   grass type, surface slopes, what sprinkler system
   is used to apply water) and how does that
   influence how I water?
2. How do I know when my lawn truly needs water?
3. How often should irrigation water be applied?
4. How much irrigation water should be applied?
5. What time of day to water?
6. How long does my irrigation system need to
   operate to apply the right amount of water?

Lets try and answer these questions
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1. WHAT TO KNOW Grasses differ in drought
tolerance and this affects water use. Table
assumes grasses grown in areas of adaptation!
Drought Tolerance Warm Season Grasses
Excellent Buffalograss
Bahiagrass
Bermudagrass
Very Good Bermudagrass hybrids
Zoysiagrass
Good St. Augustinegrass Centipedegrass Seashore paspalum
Medium
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1. WHAT TO KNOW Water use and water loss.

• Grass plants are nearly 80 water by weight!
• Grasses use water to take up soil nutrients
• Grasses cool themselves by moving water out
  through tiny pores in the leaves (a process
  called transpiration)
• Transpiration cooling is essential for the
  overall health and maintenance of turfgrass.

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More to know . . .

• Water lost though transpiration is greater under
  summer-like conditions high temperature, sunny,
  windy with low humidity.
• Water is also lost from soil reservoir by
  evaporation from soil surfaces.
• Evapotranspiration (ET) is a term that describes
  total water loss from the turf/soil system.

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2. How do I know my lawn truly needs water? Signs
of Water Stress

• Signs of water stress (wilt) will likely appear
  in localized spots in the lawn due to different
  soils, shade, or unique micro-environments.
• These spots can be hand-watered without watering
  the whole lawn
• Water stressed grasses usually show visual signs
  of wilt
• Leaf rolling
• Loss of turgor pressure. When a grass wilts
  footprints in the turf do not spring back
• Water stressed or wilted areas turn color from
  green to a bluish/purplish color to off color
  brown patches.
• Note Lawn grasses, can withstand periods of
  water stress without permanent damage to the
  plant. Try and stretch the period of time between
  irrigations. Hand watering the hot or wilted
  spots will actually make your lawn more tolerant
  of droughty conditions

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Irrigation The Plants World

• Field capacity (plant is full, soil is full,
  oxygen is fine)
• Desiccation (dry wilt)
• PWP (permanent wilting point)
• Excessive water (water logged)
• PWP (permanent wilting point)

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Wilted Turf
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3. How often should water be applied?

• Roots initiate growth from the crown.
• Roots function best when the plant is healthy and
  the soil has air in its pore spaces
• Most of the roots are usually in the upper 1/2 of
  the total root system depth - see figure to right
• Poor drainage or compacted soils reduce root
  growth and root depth

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• Lack of moisture - no water and may be in a
  drought.
• Drying out has occurred
• Roots near surface dieback first and then dieback
  progresses into the soil
• Roots only viable at deeper depths if water is
  available
• New roots can still grow out of the crown if
  water is replenished in root zone and growing
  conditions favor root growth.

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• Light watering
• Roots stay healthier near surface where
  irrigation is
• Deeper roots extract water and then decline
• Plant in depleted moisture condition can pull
  water from the deep
• Reducing water even more will greatly weaken the
  stand
• Exceptions are made in very heavy clay soils.
  Infiltration is poor so more frequent watering
  with less water is best done to get water to
  gradually move deeper into the soil

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• Saturated
• Too much rain
• Too much irrigation
• Poorly drained site
• Most soil pore spaces are filled with water
• Roots stay near the surface since that is where
  the roots find some air
• Saturated soils reduce drought tolerance
• Solution is to correct surface drainage to
  provide 1 to 2 slope

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4. How much water to apply.
1 square foot of turf

• You pay for water in gallons (Bmt.3.66/1000
  gal.)
• An inch of water over 1 acre equals 27,154
  gallons
• OR 0.62 Gallon/ft2
• 0.62 times 128 gallons 79.3 ounces
• 27,154 gallons / 1000 gal. 27.154 units X 2.44
  66.26 per watering

1 Inch 80 ounces/ft2
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How Much Water Is Applied Over Time?

• Uses Catch Cans to measure water applied over
  time in inches! Water and measure at the same
  time of day.
• Checks the uniformity of water distribution for
  each sprinkler head.
• Determines an irrigation systems application
  rate for each zone.
• Helps understand irrigation system weaknesses and
  strengths and the need for repairs.

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5. What time of day should I water?

• The best time to water is in the early morning
  (400 - 600 am)
• wind is low, water pressure is highest, consumer
  demand is low, evaporation rates are low.
• Watering in the evening
• places water droplets on the leaves for extended
  periods of time, which enhances disease.
• Water as deeply and infrequently as possible!
• If possible, water to a depth of 4-6 inches into
  the soil.
• You may have to use additional cycles on the
  irrigation system to achieve this so as to avoid
  runoff.
• Use a soil probe or screwdriver to check your
  watering depth.

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What is a Sprinkler Irrigation Audit?

• Evaluates existing irrigation system performance.
• Checks the uniformity of water distribution for
  each sprinkler head.
• Determines an irrigation systems application
  rate for each zone.
• Helps understand irrigation system weaknesses and
  strengths and the need for.

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Types of Sprinklers

• Traveling Sprinkler

• Oscillating

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Types of Sprinklers

• Impact

• rotary

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Types of Sprinklers

• Ring

• Oscillating

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Types of Sprinklers

• Spinner

• Pattern

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Ending Thought!
Does pavement really need water to survive?