Friday, May 23, 2014

Volumetric water content and soil water potential

Volumetric water content and soil water potential (or tension/suction) are two measurements we use to determine irrigation needs.

Volumetric water content
Much research has been conducted on measuring volumetric water content by Professor Dr. Michael Dukes's group (UF/IFAS ABE) in an effort to improve irrigation scheduling. Volumetric water content is often estimated using soil moisture sensors (aka soil water sensors).

Two examples of commercially available soil moisture sensor technology.
View a soil moisture sensor video

Soil water tension
Research is also conducted using tenisometeric measurements, such as tensiometers.

Example of tensiometer for measuring soil water tension.
More on using tensiometers can be found in Dr. Kati Migliaccio's EDIS publication: Using Tensiometers for Vegetable Irrigation Scheduling in Miami-Dade County

Relating these measurements
The relationship between volumetric water content and soil water potential or tension is typically established using laboratory experiments. We recently developed a video demonstrating this laboratory process.

The laboratory experiment results are used to develop a curve that relates soil water potential to volumetric water content as is shown in the EDIS publication, Alternatives of Low Cost Soil Moisture Monitoring Devices for Vegetable Production in South Miami-Dade County developed by Dr. Rafael Muñoz-Carpena (UF/IFAS ABE).

Register for more
If you are a UF graduate student and this topic interests you, be sure and register for the new graduate irrigation course ABE6933 that will be taught through distance education in the fall of 2014. Drs. Migliaccio (UF/IFAS ABE & TREC) and Dukes are developing the course and this will be one of several interesting topics they cover. A draft syllabus can be obtained by contacting either instructor.

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