Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: November 19, 2002
Publication Date: November 19, 2003
Citation: Prior S.A., Torbert, H.A., Runion, G.B., and Rogers, H.H. 2002. Effects of elevated CO2 on soybean and sorghum: residue decomposition in the field. p. 186. In USDA Symposium on Natural Resource Management to Offset Greenhouse Gas Emissions, Program and Abstracts. Raleigh, NC, November 19-21. Technical Abstract: Increasing atmospheric CO2 concentration can increase biomass production and alter tissue composition. Shifts in both quantity and quality of crop residue may alter C and N dynamics and management considerations in future CO2-enriched agroecosystems. This study was conducted to determine mass and N loss from legume (soybean [Glycine max (L.) Merr.] and non-legume (grain sorghum [Sorghum bicolor ] (L.) Moench.] residue produced under different levels of atmospheric CO2 (ambient and elevated) on a Blanton loamy sand (loamy siliceous, thermic, Grossarenic Paleudults) in Auburn, AL managed under no-till conditions. At grain maturity, plants were separated into component parts prior to dry weight determination and tissue analysis. Mass and N losses were determined from residues using the mesh bag method. Biomass production was significantly greater for soybean compared to sorghum and for elevated verses ambient CO2-grown plants. Elevated CO2 concentration did not affect percent biomass recovery, however, the greater biomass production observed under elevated CO2 resulted in more residue remaining after the overwintering period. CO2 level did not affect C:N of residue, probably due to the use of senescent plant material. The greater total N content of soybean residue, particularly when grown under elevated CO2, indicated that more N may be available to a following crop and that lower N inputs would then be required. Results from this study indicate that in a high CO2 environment, greater amount of crop residue should increase ground cover which may reduce erosion losses and improve soil physical properties.