Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/7/2003
Publication Date: 11/3/2003
Citation: PARKIN, T.B., KASPAR, T.C. 2003. TEMPERATURE CONTROLS ON DIURNAL CO2 FLUX: IMPLICATIONS FOR ESTIMATING SOIL C LOSS. SOIL SCIENCE SOCIETY OF AMERICA JOURNAL. 67:1763-1772. Interpretive Summary: Carbon dioxide (C02) is a greenhouse gas that contributes to global warming. Carbon dioxide absorption and fixation by plants is a mechanism for reducing atmospheric C02. However, when plants die and are returned to the soil, they decompose and some of the C02 they previously removed from the atmosphere is released back to the atmosphere. In order to better understand how different agricultural management practices such as crop rotations and tillage affect plant decomposition and release of CO2, scientists need better measurements of CO2 emissions from soil. Temperature has a strong influence on CO2 production in soil, so this study was done to determine the precise relationship between temperature and soil CO2 emission. We found that as temperature varies throughout the day, so does CO2 emission. We developed a mathmatical formula which enables prediction of daily CO2 emission from a single measurement. This information will aid scientists in their efforts to measure CO2 emissions from soil and evaluate agricultural management strategies to reduce CO2 emissions and increase carbon storage in soil.
Technical Abstract: Carbon dioxide flux from the soil to the atmosphere is an important component of terrestrial C cycling, and accurate estimates of CO2-C losses are critical in estimating C budgets. Chamber-based measurements of C02 flux are ofen made at infrequent intervals, thus improved interpolation between measurements must rely on better characterization of temporal variability. Diurnal variations in C02 flux have been reported, but the relationship between these variations and diurnal temperature fluctuations are not well defined. This study was done to investigate the relationships between diurnal CO2 flux and temperature at two locations, corresponding to two soil types in a no-till corn/soybean field. Automated chambers provided hourly measurements of C02 flux from April 4, 2000 through June 6, 2000. Hourly soil temperature measurements were made at the surface and at 0.05 m, along with air temperature and soil water content measurements. We observed that the temporal dynamics of C02 flux were more closely related to air temperature than to soil temperature. A variety of temperature correction algorithms to correct for biases associated with point-in-time flux measurements in estimating daily average C02 flux were evaluated. We found that a Q10=2 relationship when applied to 0.05 m soil temperature performed poorly in this regard, however, air temperature based Q10 relationships reduced time-of-day estimation biases from 28% to less than 4%.