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ARS Home » Plains Area » Bushland, Texas » Conservation and Production Research Laboratory » Soil and Water Management Research » Research » Publications at this Location » Publication #259717
Title: Crop coefficient development and application to an evapotranspiration network

Author
item MAREK, THOMAS - Texas Agrilife Research
item Howell, Terry
item SNYDER, RICHARD - University Of California
item PORTER, DANA - Texas Agrilife Research
item SCHERER, THOMAS - North Dakota State University

Submitted to: Irrigation Association Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 11/1/2010
Publication Date: 12/5/2010
Citation: Marek, T.H., Howell, T.A., Snyder, R.L., Porter, D., Scherer, T. 2010. Crop coefficient development and application to an evapotranspiration network. In: Proceedings of the 5th Decennial National Irrigation Symposium, December 5-8, 2010, Phoenix, Arizona. Paper No:IRR10-9786.2010 CDROM.

Interpretive Summary: Crop water use has been measured with accurate weighing lysimeters when they are available, and it is used to compute crop coefficient values for irrigation scheduling. A base crop water use called reference evapotranspiration is used to scale the lysimeter measurements of crop water use. This ratio is named a crop coefficient. For accurate irrigation scheduling, both values – the reference evapotranspiration and the actual crop water use – must be precisely determined. This paper describes how crop coefficients were determined and used in several regional irrigation scheduling networks. These data can improve irrigation effectiveness and conserve water as well as add profitability for the producers.

Technical Abstract: Crop coefficients derived from properly designed, operated, and maintained lysimeters provide the most accurate values throughout the growing season and are critical in the computation of hourly and daily,regionally based, crop evapotranspiration (ET) values. Multi-stage crop coefficients can be derived from continuously recording lysimeters, increasing the accuracy of both daily and seasonal irrigation crop demand estimates. These crop coefficients can be used with calculated, network based, reference crop ET to develop and disseminate locally representative crop water use estimates. Subsequently, using these accurate values in estimating crop water demand results in improved validity of regional water demand models, better assessments of proposed water policy measures, and enhanced integrity with crop consultants, water districts, and agricultural producers. This ultimately results in better (more efficient) irrigation management and water conservation.