Submitted to: Proceedings of the Central Plains Irrigation Conference
Publication Type: Proceedings
Publication Acceptance Date: February 13, 2012
Publication Date: February 21, 2012
Citation: Colaizzi, P.D., Oshaughnessy, S.A., Evett, S.R., Howell, T.A. 2012. Using plant canopy temperature to improve irrigated crop management. Proceedings of the Central Plains Irrigation Conference. February 21-22, 2012, Colby, Kansas. p. 203-223. Interpretive Summary: Effective management of irrigated crops requires knowledge of soil and plant water status. This can be measured using traditional contact sensors, but accuracy and field coverage have practical limits. Another method is by remote sensing of the plant canopy temperature, which is linked to soil and plant water status. With remote sensing, a field can be covered quickly and does not require physical contact with the plants. Plant canopy temperature can be measured by infrared thermometers. This information can be used to schedule and automate drip and center pivot irrigation systems. It can also provide maps of soil and plant water status in the field. Crops that were automatically irrigated based on plant canopy temperature were compared to crops that were irrigated based on precise measurements of soil water in the root zone. In most cases, there were no differences in crop yield, water used, or total irrigation applied. Measurement of plant canopy temperature requires much less time compared with measurement of soil water directly. Therefore, plant canopy temperature can be a useful irrigation management tool.
Technical Abstract: Remotely sensed plant canopy temperature has long been recognized as having potential as a tool for irrigation management. However, a number of barriers have prevented its routine use in practice, such as the spatial and temporal resolution of remote sensing platforms, limitations in computing capacity, algorithm accuracy, and the cost and ruggedness of sensors and related components that can transmit and receive data wirelessly. Recent advances in all of these areas have made remote sensing more feasible in providing real-time feedback of field conditions. This can potentially reduce management time, maintain crop yield and crop water productivity, and detect unusual conditions such as equipment malfunctions or biotic stress sooner. Center pivots equipped with wireless infrared thermometers (IRTs) have been found to be suitable as a remote sensing platform. Canopy temperature-based algorithms have successfully automated drip and center pivot irrigation schedules where crop yield, water use efficiency, seasonal water use, and irrigation amounts applied were comparable to irrigations scheduled manually with a field-calibrated neutron probe. Even without automation, these algorithms can provide timely and valuable information on plant and soil water status, which can improve the management of irrigated crops.