Measuring Soil Water Content Using the Cosmic-ray Neutron Probe: A Review

Abstract

Soil moisture is an important index in agricultural production and irrigation management, but difficult to measure in the field due to its spatiotemporal heterogeneity. The cosmic-ray neutron probe method developed over the past decade has emerged as new technology to non-invasively monitor soil water change at large scales and at fine time resolutions. Previous studies have shown that it is able to measure average soil water content at a given depth over an aerial area spanning several hundred meters radially. As a method to bridge the gap between point measurement and large-scale soil water estimate using remote sensing, there have been an increase in its applications in various areas including irrigation management, hydrological data assimilation and hydrological modeling. The purpose of this paper is to review the latest research progress and achievements in the use of cosmic-ray neutron method. It covers principle of the method, its monitoring range, factors influencing its accuracy and applicability, as well as possible problems and solutions. We also outline its potential application in agriculture, hydrology and other fields.

Keywords

• soil water content
• cosmic-ray neutron probe method
• landscape scale
• in-situ monitoring
• continuous monitoring