HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Stone, J. F. Articles by Read, A. A. Search for Related Content PubMed Articles by Stone, J. F. Articles by Read, A. A. Agricola Articles by Stone, J. F. Articles by Read, A. A.

Soil Moisture Determination by a Portable Neutron Scattering Moisture Meter¹

ABSTRACT

A portable, battery-powered device for measurement of soil moisture by neutron scattering has been constructed and used for field measurements. The equipment, aside from being portable, differs from previously reported devices of this type as follows: (a) A fast neutron source in the form of an annulus is placed about the center of a slow neutron detecting tube; (b) Recently developed glow transfer tubes are used for absolute neutron count determinations; (c) A calibrating volume of paraffin, which is also used as a neutron shield, is incorporated as a part of the source-detector carrying case, to permit simple field checking and standardization of the device. The detector tube is partially shielded with cadmium to reduce the vertical extent of the soil "sample" contributing to the neutron count. Field data are presented. It was found, by locating the source-detector at various depths in pipes sunk vertically into the soil, that, except for the surface 6 to 9 inches, the equipment generally gave the soil moisture per unit soil bulk volume, within the range of the standard deviation of gravimetric determinations. A single calibration curve serves for all soils tested (sand, silt loam, silty clay loam). The equipment, complete with batteries, lead and paraffin shielding, weighs 45 pounds. The shielding protects the operator against radiation hazard and is sufficient for at least 8 hours per day use, 6 days a week.

¹ Joint Publication: Journal Paper No. J-2641 of the Iowa Agr. Exp. Sta., Ames, Iowa, Project No. 998, Department of Agronomy; and contribution No. 379 of the Institute for Atomic Research, Ames, Iowa.

² Graduate Assistant in Agronomy (Soils), Professor of Soils and Physics and Research Associate in the Institute for Atomic Research, respectively. The authors acknowledge with thanks the assistance received from their colleagues during the development of this device and in particular to Messrs. G. H. Miller, A. F. Voigt and M. Voss.