Reference
Van Vuuren, M.M.I., Robinson, D., Scrimgeour, C.M., Raven, J.A. and Fitter, A.H. 2000. Decomposition of 13C-labelled wheat root systems following growth at different CO2 concentrations. Soil Biology & Biochemistry 32: 403-413.
What was done
Spring wheat (Triticum aestivum) was grown in containers fumigated with 13C-depleted CO2 at atmospheric concentrations of 350 and 700 ppm to determine the effects of elevated CO2 on carbon and nitrogen mineralization following decomposition.
What was learned
Elevated CO2 had a transient effect on carbon mineralization, where decomposition rates were initially higher than those occurring within ambient systems. However, those higher rates leveled off and ultimately were statistically indistinguishable from those obtained in ambient controls. Likewise, elevated CO2 had no significant effects on nitrogen mineralization, which was equivalent in ambient and elevated CO2 treatments.
What it means
These data suggest that as the atmospheric CO2 concentration continues to rise, decomposition rates of wheat crop residues in arable soils are not likely to change. Thus, carbon and nitrogen cycling of wheat residues should not be materially affected. Consequently, wheat monocultures will at least maintain if not increase their carbon sequestering abilities - due to the greater biomass they produce - as the air's CO2 content rises in the future.
Reviewed 11 October 2000