How much water

Discussion in 'Organic Lawn Care' started by Smallaxe, Feb 4, 2008.

  1. Smallaxe

    Smallaxe LawnSite Fanatic
    Posts: 10,082

    We all talk about over-watering but never really discuss how often grass should be watered in order to keep clients happy and the grass healthy.

    I realize that soils and temperatures along with the type of grass are all going to be variations in the timing and amounts. What I was curious about is whether there is a general rule of thumb that says how dry the soil should get before we turn the sprinkler on.

    I am specifically interested deep rooting the sod that was placed last year. It is in a good clay loam topsoil about 3 inches thick. Sod here is KBG.
     
  2. Kiril

    Kiril LawnSite Fanatic
    Posts: 18,308

    This is known as the permanently wilting point (PWP), where the plant can no longer extract water even when it is available.

    The PWP is a function of the soils and plant(s). Some plants are better adapted to pull water from the soil, others not so much.

    If your shooting blind without a moisture meter, use the observation method. During the hottest part of the season do the following.

    1) Determine the actual or desired effective rooting depth of the plants being irrigated.

    2) Irrigated to that depth (or a little deeper if you have a leaching requirement), verify with a core sample (or moisture meter if you have one)

    3) Don't irrigate again until the plants start showing signs of water deficit. At that point, you know you should be watering 1-2 days before that.

    Note -> midday wilt != water deficit

    There are other ways to determine the water requirements, but it involves calculations. The above is the easiest way for a homeowner and the occasional practitioner. If you want more info, we have discussed this topic extensively in the irrigation forum.
     
  3. Smallaxe

    Smallaxe LawnSite Fanatic
    Posts: 10,082

    That is kind of what I was thinking. Using the core sampler to check the depth of saturation and giving a period of drying out just a day or 2 shy of midday wilt. Thanks - I thought I was losing my mind.

    My clients are hearing other voices and I am out numbered by those influenced in the daily watering crowd.

    Irrigation Forum... I didn't think about that. :)
     
  4. Tim Wilson

    Tim Wilson LawnSite Senior Member
    Posts: 795

    Kiril,

    Do you know of any literature which discusses the potential microbial content of, or association with, hygroscopic water?

    Tim
     
  5. Kiril

    Kiril LawnSite Fanatic
    Posts: 18,308

    I have read some literature pertaining to this. Are you interested in how it relates to water management, bioremediation, nutrient cycling, microbial populations, or all of the above?

    Here's a couple that you might be interested in. I'll look through my poorly managed archive and see if I can find some other studies.

    Relationship Between The Chemical Structure Of Humic Substances And Their Hygroscopic Properties

    Physiology and Microbial Community Structure in Soil at Extreme Water Content

    Review of Microbial Responses to Abiotic Environmental Factors in the Context of the Proposed Yucca Mountain Repository

    Modeling Phosphorus Transport In Soil And Water

    Soil Physics and Rural Water Management – Progress, Needs and Challenges

    Salt Mineralogy of Las Vegas Wash, Nevada: Morphology and Subsurface Evaporation

    Water Potential and Aggregate Size Effects on Contact Angle and Surface Energy

    Biological Soil Crusts: Ecology and Management

    Water Controls on Soil Processes in the Southwest
     
  6. Kiril

    Kiril LawnSite Fanatic
    Posts: 18,308

    Don't use midday wilt as your indicator. Midday wilt can occur even when there is sufficient soil water available.
     
  7. Tim Wilson

    Tim Wilson LawnSite Senior Member
    Posts: 795

    Thanks Kiril,

    I'm mostly interested in long term active survival of microbes (protists mostly) in semi-drought and drought conditions.

    Tim
     
  8. Kiril

    Kiril LawnSite Fanatic
    Posts: 18,308

    OK, I'll see what I can chase down.
     
  9. Kiril

    Kiril LawnSite Fanatic
    Posts: 18,308

  10. Tim Wilson

    Tim Wilson LawnSite Senior Member
    Posts: 795

    Thanks Kiril, I really appreciate your efforts. I shall read through these and see what I find.

    Tim
     

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