ARS | Publication request: Deficit irrigation in a production setting; Canopy temperature as an adjunct to ET estimates.

Submitted to: Irrigation Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 11, 2011
Publication Date: March 1, 2012
Citation: Mahan, J.R., Young, A., Payton, P.R. 2012. Deficit irrigation in a production setting; Canopy temperature as an adjunct to ET estimates. Irrigation Science. 30(2):127.

Interpretive Summary: The amount of water that is available for agricultural use is declining globally due to the dual factors of increasing cost and physical limits on water supplies. In order to meet future demands for agricultural products water use, agricultural producers will need to make more efficient use of available water. Improved irrigation management will be an essential element in the sustainability of agriculture. Current irrigation management approaches are not well-suited to the precise management of irrigation that will be increasingly important. A direct measurement of the water use of the crop will provide the basis for improved irrigation management. In this study the use of continuous measurement of the temperature of a cotton crop was used in conjunction with a widely practiced irrigation managment approach to improve the ability of a farmer to reduce the amount of water applied to a cotton crop in Texas. The results indicate that plant temperature measurement will improve the farmer's ability to manage water on the farm using technology that is commercially available.

Technical Abstract: Water available for agricultural use is declining worldwide as a result of both declining water resources and increasing application costs. Managing crop irrigation under conditions where the water need cannot be fully met represents the future of irrigation in many areas. On the southern high plains of Texas there is interest among producers to reduce the amount of water applied to cotton. In this study, a producer's efforts to reduce water application to a cotton crop were assessed in terms of an evapotranspiration water balance that is widely used in the region. The producer was able to reduce water application to meet intended reductions relative to the evapotranspiration estimates, but depending on the method used for calculating the crop water need, he tended to overwater the crop in 2 of 3 intended deficit irrigation regimes. Analysis of continously monitored canopy temperatures provided verification of over-irrigation. Continuously monitored canopy temperature is proposed as a useful adjunct to water balance approaches to deficit irrigation management.