TheEffects of Agricultural Management Practices on Soil Organic CPools and Fluxes

Morris, S.J., S. Haile-Mariam, E.A. Paul, and G.P. Robertson

Presented at the All Scientist Meeting (2002-10-04 )

Concern over the increase in atmospheric carbon dioxide has focused research efforts on determining the quality and quantity of C that can be stored as soil organic-C (SOC) and the degree to which this storage can be used to mitigate industrial pollution. Sequestration of C in soils can be improved greatly by changes in current agricultural practices.  Determining the quantity of C that can be stored as a result is critical for governmental policy decisions. Understanding SOC dynamics requires knowledge of the size and fluxes of the SOC pools involved. Modeling has shown that first order kinetics and a three-pool concept can describe SOC dynamics effectively.  Carbon sequestration was determined for seven different agricultural systems at the Kellogg Biological Station, MI following ten years of management. SOC dynamics were evaluated using long term incubations to determine pool sizes for C including the active C pool (Ca), slow C pool (Cs) and resistant C pool (Cr).  Active fraction pool size and turnover rate differed among conventional till agriculture, perennial poplars and successional communities. Slow fraction pool turnover rate differed among conventional till agriculture, no till management, organic based low input systems and never tilled successional treatments. Changes in pool sizes and mean residence times of the C pools are indicative of C sequestration potential for this site.  Total system sequestration can be evaluated in light of changes in SOC dynamics.

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