Submitted to: Proceedings of the World Water and Environmental Resources Congress
Publication Type: Proceedings
Publication Acceptance Date: February 15, 2006
Publication Date: May 20, 2006
Citation: Howell, T.A., Evett, S.R., Tolk, J.A., Copeland, K.S., Dusek, D.A., Colaizzi, P.D. 2006. Crop coefficients developed at Bushland, Texas for corn, wheat, sorghum, soybean, cotton, and alfalfa. In: Proceedings of the World Water and Environmental Resources Congress. Examining the Confluence of Environmental and Water Concerns, May 21-25, 2006, Omaha, Nebraska. 2006 CDROM. Interpretive Summary: Water use from irrigation is critical information needed in irrigation scheduling and regional water planning. Water use from major irrigated crops in the Texas High Plains region was measured with precise weighing lysimeters during the 1988 to 2005 years. This paper presents a summary of those data in the form of crop coefficients needed to estimate crop water use. The measured data from Bushland, TX were compared with other crop coefficient data from Kimberly, ID and Davis, CA from other published sources. Crop calendars differed for selected crops, but in general, peak crop coefficients agreed with the other data souses depending on the method used to index the measured crop water use to the weather. The Bushland crop coefficients are used in evapotranspiration networks in Texas and surrounding states.
Technical Abstract: Crop coefficients derived from evapotranspiration measured with large, precise weighing lysimeters at Bushland, TX, are presented for the major regional irrigated crops -- corn, wheat, sorghum, soybean, cotton, and alfalfa. The ASCE/EWRI standardized reference evapotranspiration equation for daily weather data for short (ETos, grass) and tall (ETrs, alfalfa) crops was used as the base. Crop coefficients for both ETos and ETrs were summarized. They were generally in agreement with Kcb values from Davis, CA; Kimberly, ID; and from FAO-56.