|Sudduth, Kenneth - Ken|
Submitted to: American Society of Agricultural Engineers Meetings Papers
Publication Type: Other
Publication Acceptance Date: 7/31/2003
Publication Date: 7/31/2003
Citation: BOCKHOLD, D.L., THOMPSON, A.L., SUDDUTH, K.A., HENGGELER, J.C. 2003. IRRIGATION SCHEDULING USING INFRARED THERMOMETERS TO MEASURE CANOPY TEMPERATURE ON COTTON AND SOYBEAN [CD-ROM]. AMERICAN SOCIETY OF AGRICULTURAL ENGINEERS. PAPER NO. 03-2143.
Interpretive Summary: Significant potential exists to improve the overall profitability of irrigated farming using appropriate scheduling techniques. In certain years, some traditional methods of irrigation scheduling may result in over-application of water resulting in reduced yields and higher energy and water costs. In other years, under-irrigation results in lost potential yield. Both of these conditions result in reduced profitability. The objective of this study was to base crop irrigation scheduling in southeast Missouri on canopy temperatures as determined using infrared thermometers (IRTs). Such a scheduling method that uses canopy temperature to measure crop stress has the potential to improve scheduling by only applying water when the crop actually needs it. IRT-based irrigation scheduling has been developed for arid climates, but refinements are needed for southeast Missouri because differences between plant canopy and air temperature are more subtle in humid environments than for arid regions. We developed an IRT-based scheduling method that compared canopy temperature with a predicted canopy temperature from weather data obtained at the research site. In field experiments on cotton and soybean, the IRT-based method worked well under most conditions. There was no significant difference in crop yield compared to well-watered plots, but the IRT-based method used considerably less irrigation water. After additional testing, this new scheduling method may help irrigators in humid climates more precisely match water application to crop needs for improved efficiency and profitability.
Technical Abstract: The use of infrared thermometers to measure canopy temperatures for irrigation scheduling purposes has been successfully applied in arid environments, but has had complications in humid areas where the vapor pressure deficit is low and intermittent cloud cover occurs. In this study, four methods of irrigation scheduling were examined. These included: 1) well-watered; 2) dryland; 3) 50% of the amount applied to the well-watered treatment; and 4) irrigation based on crop-canopy temperatures. This last method compared the canopy temperature with a predicted temperature calculated from weather data collected at the site. Irrigation was triggered when the canopy temperature was above the predicted temperature for more than three consecutive hours for two consecutive days. The model under-predicted canopy temperatures in some conditions, but overall results indicate the potential for equal or higher yields with less water using this irrigation scheduling method.