Soil Sampling for Calibration of Cosmic Ray Soil Moisture Sensor, Tumbarumba Wet Eucalypt SuperSite, 2012

Soil sampling was carried out 26 Apr 2012 to calibrate the
Cosmic-ray Soil Moisture Observation sensor. A cosmic ray soil
moisture sensor was installed at the Tumbarumba Wet Eucalypt
Supersite on 03 Apr 2011 by the Australian Cosmic Ray Soil
Moisture Monitoring Network (CosmOz;
http://www.ermt.csiro.au/html/cosmoz.html). CosmOz sensors use
cosmic rays originating from outer space to measure average soil
moisture over an area of about 40 hectares to a depths of
between 10cm in wet soils to 70cm in dry soils. The system
measures fast neutrons that are produced from interactions of
cosmic rays with the atmosphere and top few meters of soil. The
intensity of these neutrons are moderated largely by water
molecules in the soil. The number of neutrons counted over a
period of time is inversely proportional to the amount of water
in the soil. To estimate volumetric water content, each system
is calibrated against soil samples that are collected from dry
and wet moisture regimes using a standard protocol. Tumbarumba
Supersite land cover: Wet sclerophyll eucalyptus forest, Land
use: native/plantation forestry, Soil type: Acidic, eutrophic
red dermosol, 3 - 4 m deep Tumbarumba soil calibration data can
be downloaded from http://cosmos.hwr.arizona.edu/Probes/StationDat/077/calib.php