CSF Water Deficit Calculator

© Cornell University, 2016. Credits: Tool Developed by Art DeGaetano & Brian Belcher.

How do I use this tool?

View our video tool tutorial on YouTube below:

Give us feedback by taking a brief survey on this tool!

  1. Instructions on Using the Tool:

    Choosing Your Location

    • Click the “Change Location” button, which pops up a dialog box with text field and a map (click the small circle button at the top right to exit if needed)
    • Create a new location by 1) entering your address, zip code, county, in the text field and clicking the “GO” button, OR 2) clicking on the map at any location in the Northeast
    • The “Confirm Location Information” dialog box will appear after clicking “GO,” along with a yellow marker at the new location.
      • Click “Save and Select” when you want to see the graph for your chosen location
      • Click “Save” when the yellow marker is in the correct location, but you want to add more locations (the color of the new symbol will be changed to blue)
      • Click “Cancel” when you do not want to keep the location

    Selecting or Deleting Additional Locations

    • You may select or delete a location from those already shown (upon clicking “Change Location”) by hovering and then clicking on an existing symbol once the white box with existing location details has appeared
    • The “Confirm Location Information” dialog will appear at the top of the map
      • Click “Select” when you want to see the graph for that location. When the dialog box closes, the color of the selected location’s marker will be changed to red, and the color of the previously selected marker will be changed to blue. The dialog box will close and your graph will appear
      • Click “Delete” to delete the location, immediately removing the marker from the map
      • Click “Cancel” when you want to do nothing

    Choosing Your Soil Water Capacity

    • Several soil water capacities are supported. By default, the High (Clay, fine textured) is selected. You may change the current soil water capacity by clicking the drop down menu and selecting either High, Medium, or Low soil water capacity. The graph will immediately update for the new variety (at the current location and date).
    • Additionally, several crop types are supported.  By default, Grass reference is selected.  To change the crop type, select the from the variety of different crop types listed in the drop down menu.

    Selecting Your Date of Planting/Budbreak

  • The “Planting/Budbreak” button selects for your “planting” or “greenup” date.
  • To select a date, click on the small green calendar to display a larger, interactive calendar from which to choose a date by clicking on it, which will automatically update the graph (switch between months by clicking the small circle in the top left and right of the calendar pop-up box that appears upon hovering with your cursor)
    • Alternatively, you may enter a “Planting/Budbreak” manually in the text box to the left of the calendar in the format YYYY-MM-DD (year-month-day) and press the enter key. The calendar will be updated and the graph will be displayed.
  • If applicable you may also select for “Last Irrigation Date”.
  • To select a date, click on the small green calendar to display a larger, interactive calendar from which to choose a date by clicking on it, which will automatically update the graph (switch between months by clicking the small circle in the top left and right of the calendar pop-up box that appears upon hovering with your cursor)
    • Alternatively, you may enter a “Last Irrigation Date” manually in the text box to the left of the calendar in the format YYYY-MM-DD (year-month-day) and press the enter key. The calendar will be updated and the graph will be displayed.
    • Below the “Last Irrigation Date” field there is a small box.  If you select the box the graph will show you water deficit results for the entire season.
  • Any irrigation amount above field capacity includes some water that is lost to drainage and not used by the plant. Therefore, irrigating to field capacity is done with water conservation in mind, especially for coarse sandy soils where drainage of any water above field capacity occurs over just a few hours.
  • Providing your last irrigation date will produce graphs in two different tabs on the right. The first tab shows calculated water deficit since the most recent day water content was observed at field capacity, along with forecasted water deficit for the subsequent 3-day period.
  • The second tab provides historical probabilities of reaching specific soil water content levels over the next 30 days, given the current water deficit.

 

Why is this tool needed?
The CSF Water Deficit Calculator estimates soil water content within a crop’s effective root zone to inform decision makers about current and forecasted water deficits. This information is used by farmers and irrigation system managers to determine the optimum frequency and duration of watering that is necessary to avoid plant stress.

How does this tool work?
Crops respond to water deficits in predictable ways at specific, measurable levels of water stress. This tool takes advantage of these relationships to monitor and predict possible water deficit and associated plant stress.

Many factors are at play in creating a proper irrigation schedule. This tool uses the following information to estimate current and forecasted water deficits:

  • Historical climatological data
  • Forecasted rainfall and evapotranspiration
  • Site-specific data that you provide about your farm, including soil type, crop type, planting dates and previous irrigation dates.

With this information, water balance calculations are performed for a soil depth of one foot (the assumed effective root zone of your crop). Precipitation, evapotranspiration, surface runoff and drainage from the root zone are all used to estimate soil water content on a daily basis. Soil water content is then compared to the soil’s field capacity to calculate the water deficit for your location. Here, the water deficit is defined as the amount of water necessary to raise the soil water content to field capacity. Color-coding of water deficits reflect the stress that plants may be experiencing at the given deficit amounts. Daily forecasted data are also used to forecast water deficits over subsequent days in a similar manner for planning purposes.

Water deficit probabilities over the next 30 days are calculated from historical data (2002-present). Using the current water deficit as model initialization together with historically observed weather during similar seasons, the water balance calculations are executed on historical data to determine the probability of observing water deficit amounts over the subsequent month.

Producers can use this tool to:

  • Plan your water applications with a goal of minimizing plant stress while maximizing water conservation.
  • Assess the probability of naturally reaching certain levels of soil water content over the next month.