Performance Factors of Neutron Moisture Probes Related to Position of Source on Detector

by J. F. Stone, Oklahoma State Univ, Stillwater, United States,
R. G. Allen, Oklahoma State Univ, Stillwater, United States,
H. R. Gray, Oklahoma State Univ, Stillwater, United States,
G. L. Dickey, Oklahoma State Univ, Stillwater, United States,
F. S. Nakayama, Oklahoma State Univ, Stillwater, United States,



Document Type: Proceeding Paper

Part of: Management of Irrigation and Drainage Systems: Integrated Perspectives

Abstract:

The performances of two commercially available neutron moisture probes with different source-detector placement were evaluated. The probes were the Troxler with the neutron source placed at the center of the detector and the Campbell-Pacific Nuclear (CPN) probe with the source mounted at the bottom of the detector. Equipment responses to non-homogeneity around the access tube and probe placement were followed. Different types of non-homogeneity were created by forming air gaps or placing high hydrogen concentration along the access tube with paraffin. Discontinuities were made at the top, mid-section and bottom of the access tube. The Troxler system tended to show greater sensitivity to water. Other differences in characteristics predicted by theory, i.e., symmetrical-shaped and narrower resolution of soil layers exhibited small differences and were not statistically different.

Subject Headings: Probe instruments | Soil water | Soil analysis | Sensitivity analysis | Moisture | Homogeneity | Statistics

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