Cosmic-Ray Neutron Probe - A New Method to Monitor Soil Moisture Content
Shamaila Zia1, Francisco Miguel Aguila Marin1, Pengnian Yang2, Wolfram Spreer1, Joachim Müller1
1University of Hohenheim, Inst. of Agricultural Engineering, Tropics and Subtropics Group, Germany
The measurement of soil moisture content at large scale involves either taking large soil samples for gravimetric analysis or installation of large number of sensors such as TDR. However, these methods are tedious, time taking and destructive. In this study a novel, non-invasive and non-destructive technique named as 'Cosmic-Ray Neutron' probe was applied which can measure the soil moisture content at large scale. The theoretical framework of Cosmic-Ray Neutron(CRN) probe is that in the atmosphere, secondary cosmic rays are generated and after colliding with the land surface, they randomly scatter and distribute both below- and above-ground. As a results, neutrons are generated which after reacting with hydrogen molecule moderate their intensity. Cosmic-ray neutron probes detect neutrons at two energies, but use “fast” Neutrons for soil moisture detection because calibration is less sensitive to the chemistry and texture of the soil. Thus, the intensity of neutrons above the ground surface strongly depends on the water mass present in soil. The measurement depth of CRN probe is 10–50 cm (depending on water content) thus, provide observations within the root zone and average soil water content over a footprint of large area of 34 hectares (a circle with a radius of 330 m).
Keywords: Calibration, China, COSMOS, cotton, soil water content
Contact Address: Shamaila Zia, University of Hohenheim, Inst. of Agricultural Engineering, Tropics and Subtropics Group, Garbenstrasse 9, 70599 Stuttgart, Germany, e-mail: shamaila.ziauni-hohenheim.de