Skip to main content
ARS Home » Research » Publications at this Location » Publication #86658
Title: CARBON ISOTOPES AND SOIL ORGANIC CARBON IN 1995-1996 WHEAT FREE-AIR CARBON DIOXIDE ENRICHMENT EXPERIMENTS AT MARICOPA, ARIZONA

Author
item LEAVITT, S - UNIV OF ARIZONA
item PENDALL, E - UNIV OF ARIZONA
item BROOKS, T - ARIZONA STATE UNIV
item PAUL, E - MICHIGAN STATE UNIV
item Kimball, Bruce
item Johnson, Hyrum

Submitted to: Annual Goldschmidt Conference
Publication Type: Abstract Only
Publication Acceptance Date: 6/2/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Changes in soil C pools in response to future elevated atmospheric CO2 concentrations are uncertain. Free-air CO2 enrichment (FACE) experiments offer realistic simulation of future environment with which to assess plant and soil acclimation. We have been using isotopic methods to determine FACE C inputs to soil organic C (SOC) pools in the Maricopa replicated wheat experiments in 1992-1993/1993-1994, and 1995- 1996/1996-1997, with special interest in the baseline SOC inputs to the control plots in the most recent experiment. Isotopic mass balance results from the 1991 FACE cotton experiment and the first two years of wheat suggest C inputs of equivalent to 10% and 5% respectively from CO2 enrichment. Isotopic results from the 1995-1996 experiment give an inconclusive picture of C inputs. This may be consistent with small (2%) inputs at the end of the initial growing season (1992-1993) of the first experiment, although 5% was measured immediately prior to the second (1993-1994) season. There may be similar influence of delayed decomposition at work in the current experiment with amplification of the signal through time as FACE plant matter decomposes and enters the SOC pools.