Soil moisture sensors for continuous monitoring

Journal of the American Water Resources Association
By: , and 



Certain physical and chemical properties of soil vary with soil water content. The relationship between these properties and water content is complex and involves both the pore structure and constituents of the soil solution. One of the most economical techniques to quantify soil water content involves the measurement of electrical resistance of a dielectric medium that is in equilibrium with the soil water content. The objective of this research was to test the reliability and accuracy of fiberglass soil-moisture electrical resistance sensors (ERS) as compared to gravimetric sampling and Time Domain Reflectometry (TDR). The response of the ERS was compared to gravimetric measurements at eight locations on the USDA-ABS Walnut Gulch Experimental Watershed. The comparisons with TDR sensors were made at three additional locations on the same watershed. The high soil rock content (>45 percent) at seven locations resulted in consistent overestimation of soil water content by the ERS method. Where rock content was less than 10 percent, estimation of soil water was within 5 percent of the gravimetric soil water content. New methodology to calibrate the ERS sensors for rocky soils will need to be developed before soil water content values can be determined with these sensors. (KEY TERMS: soil moisture; soil water; infiltration; instrumentation; soil moisture sensors.)

Study Area

Publication type Article
Publication Subtype Journal Article
Title Soil moisture sensors for continuous monitoring
Series title Journal of the American Water Resources Association
DOI 10.1111/j.1752-1688.1994.tb03274.x
Volume 30
Issue 1
Year Published 1995
Language English
Publisher Blackwell Publishing Ltd
Contributing office(s) Earth Resources Observation and Science (EROS) Center
Description 25 p.
First page 69
Last page 83
Country United States
State Arizona
Other Geospatial Walnut Gulch Experimental Watershed
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