Using infrared thermometry to estimate soil water content for a sandy soil

The objective of this research was to develop a technique to estimate soil water content from surface-minus-air temperature measurements obtained from an infrared thermometer. Two different surfaces were used: grass (clipped, Pensacola Bahiagrass) and bare soil surfaces. Soil water content was estimated to depths of 0.15, 0.30, 0.60, and 0.90 m from surface-minus-air temperature measurements with average coefficients of determination (r2/R2) of 0.62, 0.61, 0.63, and 0.60. However, to depths of 0.60 and 0.90 m this estimate was improved by using a ratio of surface-minus-air temperature measurements divided by solar radiation. A dimensionless temperature ratio, which used soil/plant surface-minus-air temperature divided by ambient air temperature was also used to estimate soil water content at different depths.