Northern Sacramento Valley ET Report – April 21, 2017

Estimated Crop Evapotranspiration (ETc) for April 14-20, 2017

This report covers the CIMIS stations in Tehama County (Gerber South), Butte County (Biggs and Durham) and Colusa County (Williams). More information on using ET Reports is available here.

  • Accumulations began on February 21, 2017, or on the approximate leafout date for a specific orchard crop.
  • Next week’s predicted ET is based on historical averages for the CIMIS station location.
  • Estimates are for orchard floor conditions where vegetation is managed by some combination of strip applications of herbicides, frequent mowing or tillage, and by mid and late season shading and water stress. Weekly estimates of soil moisture loss can be as much as 25% higher in orchards where cover crops are planted and managed more intensively for maximum growth.
  • Typical ranges in irrigation system efficiency are: Drip, 80%-95%; Micro-sprinkler, 80%-90%; Sprinkler, 70%-85%; and Border-furrow, 50%-75%.

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2 Responses to Northern Sacramento Valley ET Report – April 21, 2017

  1. Darin Pantaleoni says:

    Hi
    When the accumulated inches is in parentheses that means it’s a negative right? So the tree has that amount to use before it starts to accumulate a soil moisture loss. Am I right?

    Thanks Darin Pantaleoni

  2. Allan Fulton says:

    Yes, we placed the rainfall values in parentheses to emphasize that precipitation offsets crop evapotranspiration (ET). That said, it may not be a straight one to on relationship between ET and rainfall. Not all rainfall is effectively stored in the soil for use by the crop. It depends on the specific orchard setting and the intensity and duration of the storm. An example would be a relatively short but intense storm occurring in an orchard with slope could cause a significant amount of rainfall to runoff. In my experiences, I have found that if I credit 50 to 60 percent of the rainfall effective it guards against the soil drying out more than I might expect. This also points to the importance of checking soil moisture, either by augering and handling the soil or using soil moisture sensors. Using ET, rainfall, and irrigation records to keep a water budget provides an estimate of the soil moisture depletion and needs validation and adjustment. Best wishes for a productive season.

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