Erosion Effects on Carbon Dioxide Concentration and Carbon Flux from an Ohio Alfisol
2000
Bajracharya, Roshan M. | Lal, R. | Kimble, J. M.
Carbon dioxide concentrations in soil both reflect and influence soil biological activity and C flux to the atmosphere. We hypothesized that erosion affects CO₂ concentration and C flux from the soil surface because of its effects on soil temperature and water regimes. The soil air concentrations of CO₂ and corresponding temperature and water contents were monitored on slight (SLI), moderate (MOD), severe (SEV), and depositional (DEP) phases at 2-wk intervals between May 1996 and June 1997. The ambient soil CO₂ concentration and CO₂–C flux were determined using gas chromatograph analyses. Seasonal patterns in soil air CO₂ concentrations (ranging from a winter low of 0.56 mL L⁻¹ to a summer high of 20.90 mL L⁻¹) predominated over more subtle differences (20–80% variation) due to erosion phase effects. Significantly greater (by 12–37%) CO₂ concentrations for SEV and MOD phases over SLI and DEP were observed mainly during the summer. The effects of the erosion phase on soil CO₂ concentrations appeared to be indirect through its impacts primarily on soil temperature and, presumably, soil biological activity. Soil air CO₂ concentrations were significantly correlated with soil temperature (R ² = 0.61) and CO₂–C (R ² = 0.65) flux from the soil surface but not with soil water content. Both linear and second-order polynomial regression equations using soil temperature predicted soil CO₂ concentration.
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