CO2 enrichment and soil nitrogen effects on wheat evapotranspiration and water use efficiency

D. J. Hunsaker, B. A. Kimball, P. J. Pinter, G. W. Wall, R. L. Lamorte, F. J. Adamsen, S. W. Leavitt, T. L. Thompson, A. D. Matthias, T. J. Brooks

Research output: Contribution to journalArticlepeer-review

89 Scopus citations


Evapotranspiration (ET) and water use efficiency (WUE) were evaluated for two spring wheat crops, grown in a well-watered, subsurface drip-irrigated field under ambient (about 370 μmol mol-1 during daytime) and enriched (200 μmol mol-1 above ambient) CO2 concentrations during 1995-1996 and 1996-1997 in Free-Air CO2 Enrichment (FACE) experiments in central Arizona. The enriched (FACE) and ambient (Control) CO2 treatments were replicated in four, circular plots, each 25 m in diameter. Two soil nitrogen (N) treatments, ample (High N) and limited (Low N), were imposed on one-half of each circular plot. Wheat ET, determined using soil water balance procedures, was significantly greater in High N than Low N treatments starting in late-March (anthesis) during both years. Differences in ET between CO2 treatments during the seasons were generally small and not statistically significant, however, there was a tendency for the ET to be lower for FACE than Control under the High N treatment. The reduction in the cumulative seasonal ET due to FACE averaged 3.7 and 4.0% under High N and 0.7 and 1.2% under Low N in the first and second years, respectively. However, WUE (grain yield per unit seasonal ET) was significantly increased for the FACE treatment under both soil N treatments. For the High N treatment, the WUE was 19 and 23% greater for FACE than Control and for the Low N treatment the WUE was 12 and 7% greater for FACE than Control in the 2 years, respectively.

Original languageEnglish (US)
Pages (from-to)85-105
Number of pages21
JournalAgricultural and Forest Meteorology
Issue number2
StatePublished - Aug 8 2000


  • Crop coefficient
  • Global change
  • Soil water use
  • Subsurface drip

ASJC Scopus subject areas

  • Forestry
  • Global and Planetary Change
  • Agronomy and Crop Science
  • Atmospheric Science


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