Location: Soil Dynamics ResearchTitle: Elevated CO2 and nitrogen effects on soil CO2 flux from a pasture upon return to cultivation
Submitted to: American Society of Agronomy Branch Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 2/5/2017
Publication Date: 2/7/2017
Citation: Prior, S.A., Runion, G.B., Torbert III, H.A. 2017. Elevated CO2 and nitrogen effects on soil CO2 flux from a pasture upon return to cultivation. In: American Society of Agronomy Southern Branch Meeting Abstracts. CDROM.
Technical Abstract: Soil CO2 efflux patterns associated with converting pastures back to row crop production remain understudied in the Southeastern U.S. A 10-year study of bahiagrass (Paspalum notatum Flüggé) response to elevated CO2 was conducted using open top field chambers on a Blanton loamy sand (loamy siliceous, thermic, Grossarenic Paleudults). Plants were subjected to ambient or elevated (ambient plus 200 ppm) CO2 and grown under managed ([(NH4)2SO4] at 90 kg ha-1 3x yr-1) and unmanaged conditions (no added N), both of which are common in the Southeast. At study termination, soil CO2 flux was continuously monitored (automated carbon efflux system or ACES) following glyphosate applications and tillage to document CO2 loss associated with pasture conversion to row crop production. Concurrent measures of the herbicide termination process were documented with an active light sensor (Greenseeker® meter). Following the initial herbicide application, managed plots showed higher vigor which declined and became similar to unmanaged plots after 3 weeks; there was no CO2 effect during this period. After the second herbicide application, no GreenSeeker differences were detected, and monitoring was discontinued one week later. Cumulative soil CO2 flux was higher under elevated CO2 only for the week prior to the first herbicide application and for the period between the second herbicide application and the tillage event. The only N effect occurred during the second week after tillage (coinciding with rainfall) where daily CO2 flux was higher in managed plots. For the entire sampling period, total cumulative CO2 loss was not affected by either N or CO2 level. These findings suggest that conversion of pasture to row crop systems will not be greatly impacted by N management or atmospheric CO2 level.