Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 11/4/1999
Publication Date: N/A
Technical Abstract: Rising CO2 concentrations from agricultural activities has prompted the need to quantify greenhouse gas emissions. This work evaluated short-term tillage-induced CO2 losses measured with a large chamber using different air mixing rates and independently verified CO2 losses without the chamber. Fan number affected the CO2 flux from a freshly tilled surface. With only one fan operating (press. = -0.39 Pa), fluxes were generally lower than with four fans (press. = -1.62 Pa) suggesting more negative pressure enhanced the flux for several hours. Infrared gas analyzers were used to measure up and down wind CO2 concentrations from a plowed line source (50 m x 5.5 m-wide) perpendicular to the prevailing wind. Downwind minus upwind differences were as large as 140 umole mol**-1 after tillage and illustrate tillage-induced gas loss without the chamber. Gas exchange data using both techniques support adoption of less tillage.