Daily and seasonal evapotranspiration and yield of irrigated alfalfa in southern Idaho

Wright, James L. (1988) Daily and seasonal evapotranspiration and yield of irrigated alfalfa in southern Idaho. Agronomy Journal. 80:662-669.

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Abstract

Daily water-use data are needed for the development of modern
irrigation scheduling techniques, the optimum allocation of water
and energy resources, and improved irrigation management practices.
This field study was conducted to measure evapotranspiration
(ET) of well-irrigated alfalfa (Medicago satin L.) in the arid region
of southern Idaho. The relationship of ET to forage yield was also
investigated. The soil was Portneuf silt loam (coarse-silty, mixed,
meek Durixerollic Calciorthids) common to much of the region. Daily
and seasonal ET data were calculated for seven growing seasons
from measurements obtained with mechanical weighing lysimeters
equipped with electronic load cells. Daily alfalfa ET was highly
variable. It occasionally exceeded 10 mm d-1 and averaged 8 mm
d 1 during peak ET periods. From April through October, measured
ET averaged 1022 mm for three harvests per season for 5 yr when
soil water was nonlimiting. Corresponding average forage yield was
17.6 Mg ha1 (120 g kg-1 water content) giving an overall water
requirement of 58.1 mm (depth equivalent) to produce 1 Mg ha 1
of forage (581 m3 Mg 1) for a water-use efficiency of 17.2 kg ha
mm 1. Harvest period and seasonal ET appear linearly related to
pan evaporation and forage yield. The actual ET of well-irrigated,
high-yielding alfalfa may be as much as 50% greater than previous
estimates indicated for southern Idaho.

Item Type:	Article
NWISRL Publication Number:	0656
Subjects:	Irrigated crops > Alfalfa Water > Evapotranspiration Mass Import - autoclassified (may be erroneous)
Depositing User:	Dan Stieneke
Date Deposited:	20 Nov 2010 21:53
Last Modified:	06 Jan 2017 21:07
Item ID:	502
URI:	https://eprints.nwisrl.ars.usda.gov/id/eprint/502