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Title: ENERGY BALANCE AND EVAPOTRANSPIRATION OF WHEAT: FREE-AIR CO2 AND SOIL NITROGEN EFFECTS

Author
item Kimball, Bruce
item La Morte, Robert
item Pinter Jr, Paul
item Wall, Gerard - Gary
item Hunsaker, Douglas - Doug
item Adamsen, Floyd
item LEAVITT, S. - UNIV. OF ARIZONA
item BROOKS, T. - UNIV. OF ARIZONA

Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 11/19/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Field grown spring wheat (Triticum aestivum L. cv Yecora rojo) was exposed to CO2 concentrations enriched to 200ppm above ambient (ca. 370ppm) using free-air Co2 enrichment (FACE) apparatus. Half of each main CO2 plot received ample nitrogen (High-N; 350 kg N/ha), while the other half received 15 or 70 kg N/ha (Low-N), depending on year, intended to provide a alow-N stress. Measurements were made of net relation, Rn; soil heat flux, Go; canopy temperature, Ts; air temperature; and wind speed. Sensible heat flux, H, was calculated from the wind temperature measurements, and evapotranspiration (ET) was determined as the residual of Rn minus Go minus H. The FACE treatment increased Ts about 0.6 and 1.1 degrees Celsius at High- and Low-N, respectively. Daily total Rn was reduced by 1.3% at both levels of N. Daily ET was consistently lower in the FACE plots, by about 6.7 and 19.5% for High- and Low-N, respectively.