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Corn canopy temperatures measured with a moving infrared thermometer array

Sadler, E.J., Camp, C.R., Evans, D.E., Millen, J.A.
Transactions of the ASAE 2002 v.45 no.3 pp. 581
Zea mays, corn, canopy, temperature, measurement, thermometers, infrared radiation, sensors, center pivot irrigation, spatial variation, fields, water stress, irrigation management, irrigation rates, precision agriculture, irrigation scheduling, South Carolina
Measurement of water stress and scheduling of irrigation are both enabled by non-contact infrared thermometers (IRTs). Technological advances have miniaturized IRTs and reduced power requirements so that inexpensive self-powered units are now commercially available. The objective of this work was to test a linear array of IRT sensors mounted on a center-pivot irrigation machine, and to use this IRT array to examine spatial variation in water stress of corn under four irrigation treatments imposed on a highly variable field with a center pivot equipped for site-specific irrigation and agrochemical application. An array of 26 IRTs was mounted on the pivot, which was run dry for a full circle on 7 days during the 1999 corn growing season. Procedures were developed to adjust for time lag during the 3.5-hr measurement period. Significant differences were obtained among the varying water treatments, as expected, but also among plots within the same soil map unit and among soil map unit means. Distinct spatial patterns, not necessarily related to the 1:1200-scale soil map, were observed. These results emphasize the necessity to consider soil water relations during the development of management recommendations for site-specific agriculture.