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    How crop factor works...

    Could someone confirm for me?

    A crop factor of 0.5 waters more than a crop factor of 1.0 (twice as much). It doesn't seem right, but that's how the popup help states it

    #2
    The algorithm used to compute hourly moisture content change is the following where Crop factor is the Evap element and Efficiency is the Drain element. This means a higher crop factor will result in a faster moisture loss. I'll look at the help popup and fix it if necessary.

    nDelta = ((ET * nZoneEvapFactor(iZone) / nZoneDrainFactor(iZone)) - HourlyRain)

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      #3
      Help backwards

      Thanks Michael. The example in the popup help for crop factor is in fact backwards the way I read it.


      thanks

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        #4
        I know that crops that need more moisture, haver a higher crop factor. Isn't 1.0 supposed to be ~ KY Bluegrass ? If you had a lower water usage fescue, maybe .8, buffalo grass would be even lower, etc. I know farmers use the crop factor a lot, depending upon what crop they are growing to determine watering needs.

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          #5
          Well that helps to explain things. Is a factor of 1.0 the max value that can be used?
          Regards, Bob

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            #6
            The crop factor values are not limited so values above 1 are valid and could be used to tweak a zone that has more sun exposure while one that is primarily in the shade would have values under 1.

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              #7
              There is a lot of information here on crop coefficients.

              http://www.owue.water.ca.gov/docs/wucols00.pdf

              You can have a crop factor over 1.0 ... but that would
              be saying that the plant looses water faster than the
              reference ET, which is unlikely. But I do know some crops
              have crop factors higher equal to or higher than 1.0 ...

              (from the above .pdf link)

              The crop coefficient (Kc) is simply the fraction of water lost from the crop relative to reference evapotranspiration. Typically, crop water loss is less than reference evapotranspiration and, therefore, the crop coefficient is less than 1.0.

              For example, if water loss from corn was measured to be 4 inches in a month, and reference evapotranspiration for the same month was 8 inches, then the crop coefficient would be 0.5. Crop coefficients have been established for many crops and for turfgrasses
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