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Watering Question

Discussion in 'Turf Renovation' started by Teach123, Apr 1, 2012.

  1. Teach123

    Teach123 LawnSite Member
    Posts: 155

    I slitseeded/overseeded my property last fall with a top-quality 80/20 KBG--Rye Mix. With this early spring the turf is gorgeous. My question is about watering. Normally, with a decently established lawn I water 1x per week for about an hour per zone (depending on rainfall). However, some of the new turf isnt established and I know those roots aren't very deep. Should I be gradually going to watering deeply..meaning water lightly to get those roots that aren't deep and then gradually decrease the frequency and increase the water volume applied? The temps are fluctuating between 80's and 60's during the day and 40's and 50"s at night.

    I have an irrigation system so the watering is not the problem...

    Thanks in advance for any advise.
  2. Kiril

    Kiril LawnSite Fanatic
    Posts: 18,308

    Assuming no rain inputs.

    Interval: INTz = (AWHC * RZ * MAD) / (ETo * Kl)

    Runtime: RTz = [(60 * INTz * ETz) / ARze] * RTM
    Last edited: Apr 1, 2012
  3. Smallaxe

    Smallaxe LawnSite Fanatic
    Posts: 10,080

    The simplest thing is to 'plug' the lawn in areas of interest... turn on your sprinkler for you 'estimated time period', and after an hour or so of shutting it off,,, pull a plug and see that the water soaked the root zone or not...

    What you want is a wet root zone after irrigation, but not much beyond... Trial and error is the ONLY way to see what works in your lawn... one size does NOT fit all...

    You'll be surprised about how much sense everything makes when you plug the soil for various reasons and physically look at the soil and roots ... good luck... :)
  4. Kiril

    Kiril LawnSite Fanatic
    Posts: 18,308

    Hmmmm ..... :hammerhead:
  5. RigglePLC

    RigglePLC LawnSite Fanatic
    Posts: 12,202

    So an hour per zone...does than mean an inch of water...how much exactly? Around here irrigation companies often set the sprinklers to run 15 minutes every day. Checking the soil with a screwdriver or soil probe is useful. But there are many variables: soil type, porosity, temp, wind, humidity, rain, rooting depth, drought hardiness of grass cultivar, shade, drainage faults, use of turf (athletic, park, premium home lawn) and more.

    Around here, every day works fine--unless disease occurs--then I suggest 3 days per week. More minutes if hot--less if weather is cool.
  6. Kiril

    Kiril LawnSite Fanatic
    Posts: 18,308

    Unless you are irrigating on pure sand (i.e. a soil with almost no WHC), no reputable irrigation tech would ever water every day. That kind of scheduling is reserved for the mow and blow yahoos.

    Yes ... and more ... and they should all be taken into consideration.
  7. Dave Stuart

    Dave Stuart LawnSite Member
    Posts: 98

    Please listen to kiril's advice. Very important.
  8. Teach123

    Teach123 LawnSite Member
    Posts: 155

    Riggle: An hour usually fills up a tuna can in each zone (Depending on the water pressure and wind) Usually, the water pressure is pretty solid at 4a. I know people who irrigate everyday. They don't care that they have shallow root systems. I guess if they water each day and keep it up then same result.... green lawn. I just prefer to water to about 6' and hope the turf roots start growing deep.

    Also...KIRIL...Can I get those variable translated? I think I have figured out a few. Thanks!!

    P.S. Much of my lawn is in FULL SUN. I don't know if this makes a difference...probably
  9. Kiril

    Kiril LawnSite Fanatic
    Posts: 18,308

    Your basic water requirements on a per hydrozone (or valve zone) basis assuming no rain inputs, soil moisture content is at field capacity to start with and soil is homogeneous throughout root zone (both current and potential).

    Interval: INTz = (AWHC * RZ * MAD) / (ETo * Kl)

    INTz = Zone Interval (days)
    AWHC = Soil Plant Available Water Holding Capacity (in/foot)
    RZ = Root zone depth (feet)
    MAD = Management allowable depletion (%)
    ETo = reference evapotranspiration (in/day)
    Kl = landscape/crop coefficient (%) (see WUCOLS)​

    Runtime: RTz = [(60 * INTz * ETz) / ARze] * RTM

    RTz = Irrigation zone runtime (mins)
    INTz = Interval between irrigation events (days)
    ETz = Zone adjusted ET (in/day) --> ETz = (ETo * Kl)
    ARze = Zone effective application rate (in/hr) --> from catch can audit (most accurate)
    RTM = Runtime multiplier (a factor of DU) --> RTM = 100/DULH

    Note: Other considerations need to be made here, but this will get you started in the right direction.
  10. Smallaxe

    Smallaxe LawnSite Fanatic
    Posts: 10,080

    I'm pretty sure that at least one of those variables means "FS"... :)

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