|Pringle, H.c. Lyle|
Submitted to: American Society of Agricultural Engineers Meetings Papers
Publication Type: Proceedings
Publication Acceptance Date: 8/1/2001
Publication Date: 9/1/2001
Citation: SASSENRATH COLE, G.F., PRINGLE, H., ALARCON, V.J., THOMSON, S.J. THERMAL REMOTE SENSING FROM A MOVEABLE FIELD TRACKING SYSTEM - INSTRUMENTATION AND SYSTEM CONTROLS. AMERICAN SOCIETY OF AGRICULTURAL ENGINEERS MEETINGS PAPERS. 2001. Interpretive Summary: Several different mechanisms are under development for remote imaging of crop status. To date, no reliable system has been developed that is capable of detecting the onset of water stress in a cotton crop under the humid growing conditions of the Mid-South. This study was undertaken to explore the utility of thermal imaging systems for detection of water stress in cotton. In order to deploy the thermal system in a rapid scan over the field, a system was designed that mounted the thermal sensor to a boom, which was in turn attached to a yoke that rotated 360 degrees in the horizontal plane. The entire pivoting system was attached to a tower mounted on the front rack of an all terrain vehicle. The boom was positioned over the canopy by a hydraulic cylinder that raised and lowered the boom to the desired height. The sensing equipment could then be leveled on the support bracket at the end of the boom and focused on a given canopy region. The boom could also be moved quickly through the field to measure changes throughout the crop canopy under consistent conditions. The system responded quickly to changes in canopy temperature and was found to be a useful tool for measuring canopy parameters. Adaptation of the boom for other sensing equipment will allow additional measurements of canopy performance.
Technical Abstract: Remote sensing offers the potential for rapid, broad scale monitoring of crop status for improved management decision-making. Presently, no standard method has been adopted by producers to monitor soil moisture or crop water stress for irrigation purposes in the Mississippi Delta. We are interested in developing a rapid detection method of crop water status for irrigation scheduling. To date, no reliable remote imagery system has bee devised that adequately detects crop water status in the humid growing conditions of the Mid-South. Critical to the deployment of sensing methodologies is the potential for the technology to detect the onset of stress conditions. Soil water monitoring is commonly used to determine crop water use and schedule irrigation. While this method is reasonably reliable, it is time consuming and costly. A more reliable indicator of crop water status may be the temperature of the canopy. Thermal sensors are available that remotely sense canopy temperature. Systems based on thermal detection have been developed and used successfully in arid regions. However, the high humidity conditions of the Mid-South limit the ability of the plant to cool. Moreover, sampling of a large study area under consistent conditions of insolation requires rapid scanning. This study was undertaken to test the efficacy of a thermal sensor in detecting changes in canopy temperature under the humid growth conditions of the Mid-South. The sensor was mounted on a boom that could be positioned into the middle of the test plots and repositioned easily for rapid scanning of the crop canopy. Concurrent measurements of insolation, air temperature and georeferenced position were taken. The system was found to have a reasonably quick and accurate response to canopy temperature.