New Zealand Journal of Agricultural Research abstracts

---

Quantifying drought for humid, temperate pastures using the Crop Water Stress Index (CWSI)

C. M. FELDHAKE¹
D. M. GLENN²
W. M. EDWARDS³

D. L. PETERSON²

1Appalachian Soil and Water Conservation
Research Laboratory
Beckley, West Virginia 25802-0867, USA
2Appalachian Fruit Research Station
Kearneysville, West Virginia, USA
3North Appalachian Experimental Watershed
Coshocton, Ohio

Abstract  Pastures benefit from changes in management during periods of drought; therefore, better methods of quantifying drought would be useful. This research was conducted to determine how values of the Crop Water Stress Index (CWSI) related to measured reductions in evapotranspiration (ET) by pasture as a result of water stress. Evapotranspiration by cocksfoot was measured using a large weighing lysimeter at Coshocton, Ohio, during 1988, a very dry year, and 1989, a wet one. Evapotranspiration by cocksfoot and tall fescue was measured during 1993, at Kearneysville, West Virginia, using two large weighing lysimeters with drought simulated during the latter part of the growing season using rain-out shelters. Net radiation, wind speed, air temperature, humidity, and canopy temperature were measured at both locations to calculate potential ET and the CWSI. The relationship between CWSI and relative ET (actual divided by potential ET) was curvilinear and differed between cocksfoot and tall fescue. Under very dry conditions, the CWSI exceeded values which have been reported as the maximum for field crops. While the CWSI has the potential to be a useful tool for quantifying pasture water stress, there is a species dependency that will require further analysis.

Keywords  crop water stress index; pasture; evapotranspiration; lysimeter; drought; Festuca arundinacea; Dactylis glomerata

New Zealand Journal of Agricultural Research, 1997, Vol. 40: 17-23

0028-8233/97/4001-0017 $2.50/0 (c) The Royal Society of New Zealand 1997

PDF file of entire paper: medium quality (569K); (scanned from paper original: notes about this process)

---

This year's abstracts | Journal home page | All abstracts | Publishing home page