Submitted to: Microbial Ecology International Symposium
Publication Type: Abstract Only
Publication Acceptance Date: 5/3/2004
Publication Date: 6/1/2004
Citation: Smith, J.L., Bell, J.M., Bolton, H., Bailey, V.L. 2004. : is microbial metabolism the controlling factor for ecosystem soil carbon storage?. Microbial Ecology International Symposium.
Technical Abstract: The processes and mechanisms of soil C storage have been studied for a significant length of time. A great deal is known about soil C losses, accruals, turnover and distribution. However, much remains unknown about the mechanisms controlling intrasoil C dynamics and C cycling within specific pools. Microbial metabolism has a fundamental role in these C dynamics. Our objective was to relate initial and long-term decomposition rates of chemically different types of organic substrates in soil with C sequestration with the intent of identifying predictive indicators of C sequestering management practices. 14C labeled substrates (e.g., glucose, amino acids, carbohydrates) were added to representative soils and total CO2 and 14CO2 measured over 4 h and 24 h. The soil continued to incubate for 125 d. 14C was measured in the respired CO2, microbial biomass (15 and 125 d), and in soil after 125 d. Increasing soil N was associated with an increase in C mineralization, decreased priming (increased mineralization of SOM), and also with the highest retention of added substrate 14C. This clearly shows the coupling of the C and N cycles and the effect on C sequestration. While this observation seems intuitive, it has been poorly demonstrated in past research. In managing non-N limited soils, one must be sensitive to the fine balance that exists between sequestering C and stimulating N mineralization. Soils not limited by N will sequester more C than soils limited by N and/or C.