IRROMETER Company, Inc., has been in business since 1951, manufacturing soil moisture measuring, controlling and sampling instruments used worldwide by agricultural researchers and irrigation farmers. Principal brand names are IRROMETER® (tensiometer) and WATERMARK (electrical resistance granular matrix sensor). These instruments originated in the early part of the 20th Century, and were used by soil and plant scientists to measure soil water status in their experiments. In research applications, the use of these instruments allows the investigator to carefully manage the soil water status so as to eliminate soil water as a variable in the final result-irrespective of the purpose of the investigation (soil water status, nutrition, pest or disease incidence, etc.).
Although this technology is scientific instrumentation, the instruments are inexpensive and easy to use by farmers that irrigate. In production agriculture, the use of soil moisture based irrigation scheduling, provides a farmer with site-specific measurements of soil water status in the specific field, specific soils, specific irrigation method, and specific crop, as well as the site-specific microclimate. The proper use of this information can lead to an irrigation scheduling management program which usually results in greater production, better quality, less water, energy and fertilizer use, and helps protect water quality by eliminating run off and deep percolation loss of water due to over irrigation. Most users of this technology have the initial cost of the instrumentation returned to them in the first season of use.
Numerous interesting websites offer insight into specific applications and explanation of this instrumentation, as well as some scientific background references:
University of Nebraska "Nebraska Agricultural Water Management Demonstration Network (NWAMDN): Integrating Research and Extension/Outreach"
University of Nebraska "Enabling Producers to use Water and Energy Efficiently"
Oregon State University Malheur Experiment Station, Ontario, Oregon USA
Soil Moisture Instrumentation
Using tensiometers to make irrigation decisions in greenhouse production University of California, Davis, California USA, Dr. J. Heiner Lieth
Soil Moisture Monitoring University of California, S. Orloff, B. Hansen and D. Putnam -Includes a downloadable Excel® Graphing Spreadsheet.