Mississippi Irrigation: Using Soil Moisture Sensors to Schedule Irrigation

Soybean irrigation polypipe
Photo: Louisiana State University

It is early March, and time to think about preparing for the 2018 irrigation season. Below are short summaries of and links to information about activities that should be placed on your “to-do” list as you prepare soil moisture sensors for scheduling irrigation during the 2018 growing season.

In a Feb. 23, 2018 MCS blog article titled “It’s time to check those irrigation sensors”, Dan Roach, Extension Associate at MSU’s DREC, provides details about the necessary pre-installation preparation of Watermark Soil Moisture Sensors that will be used for irrigation scheduling. The following highlights are worth noting.

  • Watermark sensors have a useful life of about 5 years. Sensors older than this should be discarded and replaced with new sensors.
  • Watermark sensors should be pre-conditioned before installation to ensure the quickest response to changes in soil moisture after installation. The procedure for pre-installation conditioning is provided.
  • Sensors must be installed wet.

Watermark soil moisture sensors are marketed by the Irrometer Corp. The company website provides specifications and installation instructions for these sensors, as well as a brochure that provides and describes monitoring options.

Publication EC783 published by Univ. of Nebraska Extension provides a thorough treatment of the principles and operational characteristics of Watermark Soil Moisture Sensors. Pertinent topics in that publication follow.

  • Definition of soil water potential (SWP) as a measure of the energy required to extract water from soil, and how soil moisture sensor readings relate to SWP;
  • Proper pre-installation requirements and procedures for Watermark sensors;
  • Preferred locations and depth of placement of soil moisture sensors in a field to be irrigated;
  • How soil texture and associated SWP will affect amount of soil water available to plants;
  • How to accomplish downloading and interpretation of soil moisture sensor data for use in irrigation scheduling;
  • Examples of how to use soil moisture sensor readings to schedule irrigation (click here for this information for irrigating soybeans in the Midsouth).

Once you have read the above EC783 publication, keep it handy because it is likely your best reference for additional information you may need when using Watermark Sensors to schedule irrigation.

I encourage you to access an article on this website titled “Guidelines and Tools for Increased Irrigation Efficiency” to find resources pertaining to PHAUCET/Pipe Planner, Using Soil Moisture Sensors to Schedule Irrigation, and Surge Irrigation. Proper installation and use of these three tools will improve irrigation efficiency, which means that the amount of water used to achieve maximum irrigated soybean yields will be reduced.

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