Derivation of alfalfa and grass reference evapotranspiration

Wright, James L. (1996) Derivation of alfalfa and grass reference evapotranspiration. pp. 133-140. In: Camp, C.R. and Sadler, E.J. and Yoder, R.E. (eds.) Proc. Intl. Conf. Irrigation Assoc. and Intl. Committee on Irrigation Drainage. Evapotranspiration and Irrigation Scheduling. USA-TX-San Antonio, 1996/11/03-06. American Society of Agricultural Engineers.

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Abstract

The evapotranspiration (El) for a specified reference crop characterizes the rate at which
water, when readily available within the root zone, is evaporated from the plant and soil surfaces
in response to climatic conditions. Crop ET (ETc) for a given crop can be computed from
reference ET and an appropriate ET crop coefficient (Kc). Reference ET's reported here were
derived from meteorological and weighing lysimeter data obtained from 1968 through 1991 at the
USDA-ARS, ET research site in southern Idaho (Kimberly). By 1982, the Penman method had
been modified to provide an alfalfa-based reference ET (ETr); often referred to as the 1982
Kimberly-Penman method, for use with irrigated crops in arid regions. Now, because of worldwide
interest in using a reference ET based on a clipped grass surface (ETo), wind functions,
similar in nature to those used to compute ETr, have been derived to compute daily grass
reference ET (ETrg), for 'Fawn' tall fescue grass, using the same meteorological data as used to
compute ETr. On a seasonal basis, ETrg was 83% of ETr.

Item Type:	Conference or Workshop Item (Paper)
NWISRL Publication Number:	0928
Subjects:	Irrigated crops > Alfalfa Water > Evapotranspiration Mass Import - autoclassified (may be erroneous)
Depositing User:	Dan Stieneke
Date Deposited:	20 Nov 2010 21:55
Last Modified:	22 Nov 2016 22:08
Item ID:	862
URI:	https://eprints.nwisrl.ars.usda.gov/id/eprint/862