Submitted to: ASA-CSSA-SSSA Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: October 1, 2003
Publication Date: November 2, 2003
Citation: STOTT, D.E., ROGERS JR, H.H., PRIOR, S.A. ELEVATED CO2 IMPACTS ON MICROBIAL ACTIVITY AND SOIL ORGANIC MATTER IN A SOUTHEASTERN U.S. SOIL. CD-ROM. DENVER, CO: AMERICAN SOCIETY OF AGRONOMY PROCEEDINGS. 2003. Technical Abstract: The continuing rise in atmospheric CO2 has important implications for terrestrial carbon processes. As part of a larger project, we studied the C storage and changes in microbial activity in two agro-ecosystems, soybean and sorghum, on a Blanton Loamy Sand soil located in Auburn, AL. Treatments consisted of 360 ppm CO2 in ambient atmosphere, 360 ppm CO2 in open-top chambers and 720 ppm CO2 in open-top chambers. Soil was sampled after the sixth year. Cores were divided into 4 depth samplings: 0-5, 5-10, 10-15 and 15-30 cm. Soil enzymatic activities measured included: beta-glucosidase, arylsulfatase, phosphatase, and fluorescein diacetate hydrolase. Total C and N, dissolve organic C and carbohydrate C were also measured. Susceptibility to crusting and surface sealing was determined using a fall-velocity tube. Differences in activity with depth were significant, with the surface layer having the greater activity and C sequestration. Differences in enzymatic activity and sealing potential between CO2 treatments and the control were significantly higher in the surface layer, however there were no differences in C content. Despite a six-year exposure to elevated CO2, this loamy sand from the southeastern US was unable to sequester additional C, probably due to the warm climate and rapid organic C turnover.