Development of a low cost infrared thermometry system for agricultural applications

Authors: Mahan, James; Yeater, Kathleen

Submitted to: Computers and Electronics in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/14/2008
Publication Date: 7/9/2008
Citation: Mahan, J.R., Yeater, K.M. 2008. Development of a low cost infrared thermometry system for agricultural applications. Computers and Electronics in Agriculture. 64(2): 262-267.

Interpretive Summary: Knowledge of plant temperatures can be used to manage important aspects of crop production. Infrared thermometers are useful tools for monitoring plant temperatures however the cost of the widely used industrial-quality devices is an impediment to their use in production agriculture. While low-cost consumer-quality infrared thermometers have recently become available, their suitability in production agriculture has not been investigated. Consumer-quality infrared thermometers were incorporated into a low-cost wireless temperature monitoring system for use in production agriculture. Laboratory and field testing demonstrated the suitability of consumer-quality infrared thermometers for use in production agriculture. The results of this study demonstrate that a 10-fold reduction in the cost of infrared thermometers is attainable with no reduction in accuracy. Given the cost reduction per unit the end user will now have the option of deploying a larger number of sensors for the same cost as the previous devices or using the same number of sensors at a lower overall cost.

Technical Abstract: Plant canopy temperature is used in many studies of plant/environment interactions. Non-contact measurement of plant canopy temperature is often accomplished through the use of radiometric surface thermometers commonly referred to as infrared thermometers. Industrial-quality infrared thermocouples are widely available and often used in agricultural research. While research on canopy temperature has resulted in management tools for production agriculture, the cost of industrial-quality infrared thermocouples has limited their use in production agriculture settings. In this paper we evaluate the use of a low-cost consumer-quality infrared thermocouple device as a component of a wireless thermal monitoring system designed for use in a production agriculture setting. The performance of industrial-quality and low-cost consumer quality devices were compared under controlled constant temperature conditions and under field conditions using both grass and cotton canopies. Results demonstrate that under controlled constant-temperature conditions the two types of IRT’s are “significantly the same” at 10°C, 20°C and 30°C and are “significantly not the same” at 40°C and 50°C. Across the entire temperature range, the consumer-quality IRT temperature reading is closer to the thermocouple reading than the industrial-quality IRT. Comparison of the 15-minute means of 5 industrial-quality IRT devices and 6 consumer-quality IRT devices monitoring a grass canopy during June of 2007 and a cotton canopy during September 2007 indicated that the two types of devices are functionally equivalent over 13°C to 35°C range of the measurement period. Over a range of temperatures experienced by plants in temperate regions (10°C to 50°C), the two types of devices would not differ significantly. The results indicate that the consumer-quality infrared thermometer may be suitable for use in production agricultural applications.