Statistical Parameters and Reproducibility of the Neutron Method of Measuring Soil Moisture1
- John F. Stone,
- R. H. Shaw and
- Don Kirkham2
The neutron device used in the study was essentially that of Stone et al., Soil Sci. Sco. Am. Proc. 19:419-423. 1955. Reproducibility (that is, repeat performance at a given location) of the neutron device was evaluated in the laboratory and in the field. Observed coefficients of variation for laboratory and field were about 1.5% to 2.5%. Random counting error component accounted for most of this percentage.
In comparing gravimetric sampling with neutron measurements at the same locations, a rather poor agreement was observed within locations, but overall average difference in indicated moisture was < 0.1 inch of water per 6-inch soil depth. Poor individual agreement is believed to be due to limitations of bulk density determination and not to the neutron device.
A comparison of the relative abilities of the aravimetric and neutron methods to evaluate moisture in a set of plots where sampling locations were randomized indicates that use of seven gravimetric sites for each neutron site gives a comparable standard error of the mean.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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