Impacts of Soil Organic Matter Fractions and Management on CO2 Efflux In Long-Term Experimental Plots.

There has been great interest on the role of carbon dioxide (CO₂) in global climate change in recent years. The concentration of atmospheric CO₂ has been increasing significantly since the Industrial Revolution. It has been established that fossil fuel combustion, forestation, changes in land management and other factors contribute to atmospheric CO₂ enrichment. More carbon is contained in soil than vegetation and the atmosphere combined, and soil is a leaking reservior of CO₂. Even though soil CO₂ efflux has been studied, there is limited information that relates soil carbon fractions, C, N and fulvic acid extractable organic functional groups to CO₂ efflux. The objective of this study was to establish the impacts of different soil organic matter (SOM) fractions, fertilizer treatments and crop rotations on CO₂ efflux.  We measured light, heavy and total organic matter fractions, C, N and CO₂ efflux in the long-term cultivated plots at Auburn University's Old and Cullars Rotations using standard instruments and procedures. We also characterized fulvic acid extractable soil organic functional groups.  Soil depth, fertilizer treatment and rotation have significant impact on the parameters we measured.  Our data also indicated that the CO₂ efflux for the summer seasons were greater than their corresponding fall season for 2008, and the 2010 summer measurements were greater than the summer of 2008. In general, CO₂ efflux is affected by many factors that are interrelated and interdependent. Detailed lab procedures and data will be presented, and the results will be discussed.