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United States Department of Agriculture

Agricultural Research Service

Title: Soil Water Measurement by Neutron Thermalization

Author
item Evett, Steven

Submitted to: Encyclopedia of Water Science
Publication Type: Book / Chapter
Publication Acceptance Date: December 11, 2001
Publication Date: August 1, 2003
Citation: EVETT, S.R. SOIL WATER MEASUREMENT BY NEUTRON THERMALIZATION. STEWART, B.A., HOWELL, T.A., EDITORS. MARCEL-DEKKER, INC., NEW YORK, NY. ENCYCLOPEDIA OF WATER SCIENCE. 2003. P. 889-893.

Interpretive Summary: This chapter concisely describes the neutron thermalization method for soil water content measurement, one of the most commonly used non-destructive methods, and arguably still the best available method for deep profile measurements. Principles, theory, and possible problems are described. A novel device for ensuring accuracy of depth placement of the measurement probe is described. Calibration and attainable precision and accuracy are discussed. The chapter ends with a discussion of advantages and limitations of the method. The chapter will be a useful reference for scientists, engineers, agricultural consultants and students needing to know more about the method; and it provides seventeen references for further reading.

Technical Abstract: This chapter describes the neutron thermalization method for soil water content measurement, one of the most commonly used non-destructive methods. Principles, theory, major interferences, and statistics of neutron emission are discussed. Solutions to possible problems are given. Equipment and its use are described. A discussion of measurement volume is included, along with comparisons to other non-destructive methods. A novel device ensuring accurate depth placement of the measurement probe is described. Field calibration typically results in calibration root mean squared errors <0.01 m**3/m**3. Methods for checking calibrations are described. Safety and environmental concerns are addressed; and the chapter ends with a discussion of advantages and limitations of the method. The chapter will be a useful reference for scientists, engineers, students and agricultural consultants needing to know more about the method. The seventeen references sallow for more in-depth reading.

Last Modified: 11/27/2014
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