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United States Department of Agriculture

Agricultural Research Service

Title: Neutron Moisture Meters

Author
item Evett, Steven

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: February 6, 2007
Publication Date: February 1, 2008
Citation: Evett, S.R. 2008. Neutron moisture meters. In: Evett, S.R., Heng, L.K., Moutonnet, P., Nguyen, M.L., editors. Field Estimation of Soil Water Content: A Practical Guide to Methods, Instrumentation, and Sensor Technology. IAEA-TCS-30. International Atomic Energy Agency, Vienna, Austria. ISSN 1018-5518. p. 39-54.

Interpretive Summary: As a chapter in a book to be published by the International Atomic Energy Agency/FAO Joint Division, this publication will reach a world wide audience of agriculturalists, including scientists and practitioners. It contains detailed information on how to accurately sense soil water content using the neutron moisture meter. Accurate soil water content measurements to considerable depth are required for irrigation and environmental management. The chapter provides insight into problems commonly encountered in using the neutron method, a method that is practically insensitive to soil salinity and temperature changes that interfere with other common methods. Guidance on calibration for different soil layers and types is given. Instruction on data recording and analysis is also given. The theory and practice of the NMM for soil water sensing is presented, with useful inferences drawn for solving measurement problems. A procedural guide is given for calibrating, installing and using the equipment; as is guidance for choosing third-party equipment that improves the accuracy of the method. Attention is given to solutions to common problems of cabling, choice and installation of access tubes, repair and maintenance, and use in problem soils. Particular emphasis is given to safety and quality assurance practices that keep radiation exposure as low as reasonably achievable while producing high quality results.

Technical Abstract: This chapter, in a book to be published by the International Atomic Energy Agency/FAO Joint Division, provides detailed information on how to accurately sense soil water content with the neutron moisture meter (NMM). It provides insight into problems commonly encountered in using the neutron method, a method that is practically insensitive to soil salinity and temperature changes that interfere with other common methods. Presented are methods of calibration that ensure a wide range of water contents for different soil layers and types. Guidance on data recording and analysis is also given. The theory and practice of the NMM for soil water sensing is presented, with useful inferences drawn for solving measurement and quality assurance problems. A procedural guide is given for calibrating, installing and using the equipment; as is guidance for choosing third-party equipment that improves the accuracy of the method. Attention is given to solutions to common problems of cable maintenance, choice and installation of access tubes, general repair and maintenance, and use in problem soils. Particular emphasis is given to safety and quality assurance practices that keep radiation exposure as low as reasonably achievable while producing high quality results.

Last Modified: 4/18/2014
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